CALVERT MANAGEMENT SERIES - Form 485BPOS SEC filing

Calvert Responsible Municipal Income Fund2Prospectus dated May 1, 2024

Portfolio Turnover

Principal Investment Strategies

Under normal market conditions, at least 80% of the income from the Fund will be exempt from federal income tax (the “Tax-Exempt 80% Policy”). In complying with this policy, the Fund normally expects to invest at least 80% of its net assets in municipal obligations, the interest on which is exempt from regular federal income tax and federal alternative minimum tax (the “Municipal Obligations 80% Policy”). The Fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in issuers that the investment adviser determines operate in a manner consistent with or promote The Calvert Principles for Responsible Investment (the “Principles”) (the “Principles 80% Policy”). The Principles provide a framework for the investment adviser’s evaluation of investments considering environmental, social and governance (“ESG”) factors. The Principles seek to identify issuers that operate in a manner that is consistent with or promote: environmental sustainability and resource efficiency; equitable societies and respect for human rights; and accountable governance and transparency, among other factors. For additional information, please refer to “Appendix A: The Calvert Principles for Responsible Investment” in this Prospectus.

At least 65% of the Fund’s net assets normally will be invested in municipal obligations rated at least investment grade at the time of investment (which are those rated Baa or higher by Moody’s Investors Service, Inc. (“Moody’s”), or BBB or higher by either S&P Global Ratings (“S&P”) or Fitch Ratings (“Fitch”)) or, if unrated, determined by the investment adviser to be of at least investment grade quality. The Fund may invest up 35% of its net assets in obligations rated below investment grade and in unrated obligations considered to be of comparable quality by the investment adviser (“junk bonds”). For purposes of rating restrictions, if municipal obligations are rated differently by two or more rating agencies, the highest rating is used.

The Fund may invest in municipal obligations without limitation as to their maturity or duration, and there is no upper or lower limit on the Fund’s average maturity or average duration. At the sole discretion of the Fund’s portfolio managers, the Fund may seek out attractive investment opportunities across the yield curve.

The Fund may invest in a variety of municipal obligations, including obligations issued by state and local issuers as well as U.S. territories, various types of revenue debt, special tax obligations, qualified private activity bonds, municipal leases, principal only municipal investments and certificates of participation in such investments. The Fund may invest 25% or more of its total assets in certain types of municipal obligations (such as general obligations, municipal leases, principal only municipal investments, revenue bonds and industrial development bonds) and in one or more economic sectors (such as housing, hospitals, healthcare facilities or utilities). The Fund may invest in pooled investment vehicles, including exchange-traded funds (“ETFs”), in order to seek exposure to the municipal markets or municipal market sectors. Such investments in pooled investment vehicles will not be counted toward the Principles 80% Policy or toward the Tax-Exempt 80% Policy but may be counted toward the Municipal Obligations 80% Policy if the vehicle invests at least 80% of its net assets in the type of securities included in the Municipal Obligations 80% Policy. The Fund may invest in restricted securities.

The Fund may invest in other debt obligations, including (but not limited to) taxable municipal obligations, U.S. Treasury securities and obligations of the U.S. Government, its agencies and instrumentalities (“Agency Securities”) provided that not more than 20% of its income will be taxable. Interest earned from taxable investments will be taxed as ordinary income. Dividends attributable to interest on certain private activity bonds are included in federal alternative minimum tax for individuals and corporations. The Fund may purchase or sell futures contracts for hedging purposes. The Fund may also purchase or sell residual interest bonds. The Fund may also lend its securities.

The investment adviser’s process for selecting obligations for purchase and sale includes an evaluation of an obligation’s creditworthiness and consideration of the responsible investing criteria described below. In evaluating creditworthiness, the investment adviser will consider ratings assigned by rating agencies and generally perform additional credit and investment analysis. The investment adviser will also consider the relative value of the obligation in the market.

Responsible Investing. In selecting investments for the Fund, the Fund’s investment adviser is guided by the Principles (a copy of which is included as an appendix to the Fund’s Prospectus), which provide a framework for considering ESG factors. The Fund’s investments include municipal securities that the Fund’s adviser believes may have a positive

Calvert Responsible Municipal Income Fund3Prospectus dated May 1, 2024

environmental and/or social impact, such as obligations that fund education, healthcare, community services, housing, water, public transportation and other public purposes.

Principal Risks

Market Risk. The value of investments held by the Fund may increase or decrease in response to social, economic, political, financial, public health crises or other disruptive events (whether real, expected or perceived) in the U.S. and global markets and include events such as war, natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest. These events may negatively impact broad segments of businesses and populations and may exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Monetary and/or fiscal actions taken by U.S. or foreign governments to stimulate or stabilize the global economy may not be effective and could lead to high market volatility. No active trading market may exist for certain investments held by the Fund, which may impair the ability of the Fund to sell or to realize the current valuation of such investments in the event of the need to liquidate such assets.

Municipal Obligations Risk. The amount of public information available about municipal obligations is generally less than for corporate equities or bonds, meaning that the investment performance of municipal obligations may be more dependent on the analytical abilities of the investment adviser than stock or corporate bond investments. The secondary market for municipal obligations also tends to be less well-developed and less liquid than many other securities markets, which may limit the Fund’s ability to sell its municipal obligations at attractive prices. The differences between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress. Less liquid obligations can become more difficult to value and be subject to erratic price movements. The increased presence of non-traditional participants (such as proprietary trading desks of investment banks and hedge funds) or the absence of traditional participants (such as individuals, insurance companies, banks and life insurance companies) in the municipal markets may lead to greater volatility in the markets because non-traditional participants may trade more frequently or in greater volume.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Duration measures the time-weighted expected cash flows of a fixed-income security, while maturity refers to the amount of time until a fixed-income security matures. Generally, securities with longer durations or maturities are more sensitive to changes in interest rates than securities with shorter durations or maturities, causing them to be more volatile. Conversely, fixed-income securities with shorter durations or maturities will be less volatile but may provide lower returns than fixed-income securities with longer durations or maturities. In a rising interest rate environment, the duration of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate. Certain instruments held by the Fund were historically based on the London Interbank Offered Rate (“LIBOR”), which was the average offered rate for various maturities of short-term loans between certain major international banks. LIBOR historically was used throughout global banking and financial industries to determine interest rates for a variety of financial instruments (such as debt instruments and derivatives) and borrowing arrangements. Upon a determination by regulators to phase out the use of LIBOR, market participants have been transitioning to the use of alternative reference rates over the past few years. As of June 30, 2023, the administrator of LIBOR ceased publishing LIBOR settings. The impact of the transition away from LIBOR on certain debt securities, derivatives and other financial instruments that utilize LIBOR remains uncertain. The transition away from LIBOR and the use of replacement rates may adversely affect transactions that used LIBOR as a reference rate, financial institutions, funds and other market participants that engaged in such transactions, and the financial markets generally.

Credit Risk. Investments in municipal obligations and other debt obligations (referred to below as “debt instruments”) are subject to the risk of non-payment of scheduled principal and interest. Changes in economic conditions or other circumstances may reduce the capacity of the party obligated to make principal and interest payments on such instruments and may lead to defaults. Such non-payments and defaults may reduce the value of Fund shares and income distributions. The value of debt instruments also may decline because of concerns about the issuer’s ability to make principal and interest payments. In addition, the credit ratings of debt instruments may be lowered if the financial condition of the party obligated to make payments with respect to such instruments deteriorates. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel, which may increase the Fund’s operating expenses and adversely affect net asset value. Municipal obligations may be insured as to principal and interest payments. If the claims-paying ability or other rating of the insurer is downgraded by a rating agency, the value of such obligations may be negatively affected.

Calvert Responsible Municipal Income Fund4Prospectus dated May 1, 2024

Lower Rated Investments Risk. Investments rated below investment grade and comparable unrated investments (sometimes referred to as “junk”) are speculative because of increased credit risk relative to other fixed income investments. Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments. An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs. Lower rated investments typically are subject to greater price volatility and illiquidity than higher rated investments.

Derivatives Risk. The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the security, instrument, index, currency, commodity, economic indicator or event underlying a derivative (“reference instrument”), due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying reference instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying reference instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in (or be unable to achieve) the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment. A derivative investment also involves the risks relating to the reference instrument underlying the investment.

Sector and Geographic Risk. Because the Fund may invest a significant portion of its assets in obligations issued in one or more states and/or U.S. territories and in certain types of municipal obligations and/or in certain sectors, the value of Fund shares may be affected by events that adversely affect a state, U.S. territory, sector or type of obligation and may fluctuate more than that of a more broadly diversified fund. General obligation bonds issued by municipalities can be adversely affected by economic downturns and the resulting decline in tax revenues. Revenue bonds can be adversely affected by the negative economic viability of the facility or revenue source.

Pooled Investment Vehicles Risk. Pooled investment vehicles are open- and closed-end investment companies and exchange-traded funds (“ETFs”). Pooled investment vehicles are subject to the risks of investing in the underlying securities or other investments. Shares of closed-end investment companies and ETFs may trade at a premium or discount to net asset value and are subject to secondary market trading risks. In addition, the Fund will bear a pro rata portion of the operating expenses of a pooled investment vehicle in which it invests.

Risks of Principal Only Investments. Principal only investments entitle the Fund to receive the stated value of such investment when held to maturity. The values of principal only investments are subject to greater fluctuation in response to changes in market interest rates than obligations that pay interest currently. The Fund will accrue income on these investments and distribute that income each year. The Fund may be required to sell other investments to obtain cash needed for such income distributions.

U.S. Government Securities Risk. Different types of U.S. government securities are subject to different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. Although certain U.S. Government-sponsored agencies (such as the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association) may be chartered or sponsored by acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. With respect to U.S. government securities that are not backed by the full faith and credit of the United States, there is a risk that the U.S. Government will not provide financial support to such U.S. government agencies, instrumentalities or sponsored enterprises if not obligated to do so by law. U.S. Treasury and U.S. Government agency securities generally have a lower return than other obligations because of their higher credit quality and market liquidity.

Risk of Residual Interest Bonds. The Fund may enter into residual interest bond transactions, which expose the Fund to leverage and greater risk than an investment in a fixed-rate municipal bond. The interest payments that the Fund receives on the residual interest bonds acquired in such transactions vary inversely with short-term interest rates, normally decreasing when short-term rates increase. The value and market for residual interest bonds are volatile and such bonds may have limited liquidity. As required by applicable accounting standards, the Fund records interest expense as a liability with respect to floating-rate notes and also records offsetting interest income in an amount equal to this expense.

Calvert Responsible Municipal Income Fund5Prospectus dated May 1, 2024

Leverage Risk. Certain Fund transactions may give rise to leverage. Leverage can result from a non-cash exposure to an underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. The use of leverage may cause the Fund to maintain liquid assets or liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations. Leverage may cause the Fund’s share price to be more volatile than if it had not been leveraged, as certain types of leverage may exaggerate the effect of any increase or decrease in the value of the Fund’s portfolio securities. The loss on leveraged investments may substantially exceed the initial investment.

Tax Risk. Income from tax-exempt municipal obligations could be declared taxable because of changes in tax laws, adverse interpretations by the relevant taxing authority or the non-compliant conduct of the issuer of an obligation.

Liquidity Risk. The Fund is exposed to liquidity risk when trading volume, lack of a market maker or trading partner, large position size, market conditions, or legal restrictions impair its ability to sell particular investments or to sell them at advantageous market prices. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. These effects may be exacerbated during times of financial or political stress.

Restricted Securities Risk. Unless registered for sale to the public under applicable federal securities law, restricted securities can be sold only in private transactions to qualified purchasers pursuant to an exemption from registration. The sale price realized from a private transaction could be less than the Fund’s purchase price for the restricted security. It may be difficult to identify a qualified purchaser for a restricted security held by the Fund and such security could be deemed illiquid. It may also be more difficult to value such securities.

Securities Lending Risk. Securities lending involves a possible delay in recovery of the loaned securities or a possible loss of rights in the collateral if the borrower fails financially. The Fund could also lose money if the value of the collateral decreases.

Risks Associated with Active Management. The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions and there is no guarantee that such decisions will produce the desired results or expected returns.

Responsible Investing Risk. Investing primarily in responsible investments carries the risk that, under certain market conditions, the Fund’s performance may be impacted. The application of responsible investment criteria may affect the Fund’s exposure to certain sectors or types of investments, and may impact the Fund’s relative investment performance depending on whether such sectors or investments are in or out of favor in the market. An investment’s ESG performance or the investment adviser's assessment of such performance may change over time, which could cause the Fund to temporarily hold securities that do not comply with the Fund’s responsible investment criteria. In evaluating an investment, the investment adviser is dependent upon information and data that may be incomplete, inaccurate or unavailable, which could adversely affect the analysis of the ESG factors relevant to a particular investment. Successful application of the Fund’s responsible investment strategy will depend on the investment adviser's skill in properly identifying and analyzing material ESG issues.

General Fund Investing Risks. The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund. The Fund is designed to be a long-term investment vehicle and is not suited for short-term trading. Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective(s). In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. The Fund relies on various service providers, including the investment adviser and sub-adviser, if applicable, in its operations and is susceptible to operational, information security and related events (such as public health crises, cyber or hacking attacks) that may affect the service providers or the services that they provide to the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index. The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Calvert Responsible Municipal Income Fund6Prospectus dated May 1, 2024

CRM became the investment adviser to the Fund on December 31, 2016. Performance for periods prior to such date is that of the Fund's former investment adviser. The Fund’s performance reflects the effects of expense reductions. Absent these reductions, performance would have been lower. Updated Fund performance information can be obtained by visiting www.calvert.com.

Calendar year-by-year total return (Class A)

Year	2014	2015	2016	2017	2018	2019	2020	2021	2022	2023
Year Total Return	7.47%	2.93%	-0.42%	5.00%	0.54%	7.10%	4.38%	0.19%	-8.20%	5.50%

For the ten years ended December 31, 2023, the highest quarterly total return for Class A was 7.18% for the quarter ended December 31, 2023 and the lowest quarterly return was -6.09% for the quarter ended March 31, 2022.

Average Annual Total Returns as of December 31, 2023	One Year	Five Years	Ten Years	Life of Fund
Class A Return Before Taxes	2.04%	0.97%	2.01%	4.86%
Class A Return After Taxes on Distributions	2.00%	0.93%	1.99%	3.44%
Class A Return After Taxes on Distributions and Sale of Class A Shares	2.26%	1.13%	2.05%	3.45%
Class C Return Before Taxes	3.71%	0.88%	-	1.24%
Class I Return Before Taxes	5.75%	1.90%	2.60%	5.01%
Bloomberg Municipal Bond Index (reflects no deduction for fees, expenses or taxes)	6.40%	2.25%	3.03%	6.06%

These returns reflect the maximum current sales charge for Class A (3.25%) and any applicable contingent deferred sales charge (“CDSC”) for Class C. Effective November 5, 2020, Class C shares automatically convert to Class A shares eight years after purchase. Prior to November 5, 2020, Class C shares automatically converted to Class A shares ten years after purchase. The Class C and Class I performance shown above for the period prior to July 15, 2015 (commencement of operations for each such class) is the performance of Class A shares at net asset value without adjustment for any differences in the expenses of the classes. If adjusted for such differences, returns would be different. BLOOMBERG® is a trademark and service mark of Bloomberg Finance L.P. and its affiliates (collectively “Bloomberg”). BARCLAYS® is a trademark and service mark of Barclays Bank Plc (collectively with its affiliates, “Barclays”), used under license. Bloomberg or Bloomberg’s licensors, including Barclays, own all proprietary rights in the Bloomberg Barclays Indices. Neither Bloomberg nor Barclays is affiliated with CRM, and neither approves, endorses, reviews or recommends the Fund. Neither Bloomberg nor Barclays guarantees the timeliness, accurateness or completeness of any data or information relating to Bloomberg Municipal Bond Index, and neither shall be liable in any way to CRM, investors in the Fund or other third parties in respect of the use or accuracy of Bloomberg Municipal Bond Index or any data included therein. Investors cannot invest directly in an Index.

After-tax returns are calculated using the highest historical individual federal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions and may differ from those shown. After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities. After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares. Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and Sale of Fund Shares for a period may be greater than or equal to Return Before Taxes and/or Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.

Management

Investment Adviser. Calvert Research and Management (“CRM” or the “Adviser”).

Portfolio Managers

Cynthia J. Clemson, Managing Director of Morgan Stanley and Vice President of CRM, has managed the Fund since December 2016.

William J. Delahunty, Jr., Managing Director of Morgan Stanley and Vice President of CRM, has managed the Fund since October 2021.

Calvert Responsible Municipal Income Fund7Prospectus dated May 1, 2024

Purchase and Sale of Fund Shares

You may purchase, redeem or exchange Fund shares on any business day, which is any day the New York Stock Exchange is open for business. You may purchase, redeem or exchange Fund shares either through your financial intermediary or (except for purchases of Class C shares by accounts with no specified financial intermediary) directly from the Fund either by writing to the Fund, P.O. Box 219544, Kansas City, MO 64121-9544, or by calling 1-800-368-2745. The minimum initial purchase or exchange into the Fund is $1,000 for each Class (with the exception of Class I) and $1,000,000 for Class I (waived in certain circumstances). There is no minimum for subsequent investments.

Tax Information

The Fund’s distributions are expected to primarily be exempt from regular federal income tax. However, the Fund may also distribute taxable income to the extent that it invests in taxable municipal obligations or other obligations which generate taxable income. Distributions of any net realized gains are expected to be taxable.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund’s shares through a broker-dealer or other financial intermediary (such as a bank) (collectively, “financial intermediaries”), the Fund, its principal underwriter and its affiliates may pay the financial intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the financial intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

Calvert Responsible Municipal Income Fund8Prospectus dated May 1, 2024

Investment Objective & Principal Policies and Risks

The investment objective and principal investment policies and risks of the Fund are described in its Fund Summary. Set forth below is additional information about such policies and risks, as well as information about other types of investments and practices in which the Fund may engage from time to time. See also “Strategies and Risks” in the Statement of Additional Information (“SAI”).

Definitions. As used herein, the following terms have the indicated meaning: “1940 Act” means the Investment Company Act of 1940, as amended; “1933 Act” means the Securities Act of 1933, as amended; “Code” means the Internal Revenue Code of 1986, as amended; “ERISA” means the Employee Retirement Income Security Act of 1974, as amended; and “investment adviser” means the Fund’s investment adviser but if the Fund is sub-advised, it refers to the sub-adviser(s) providing day-to-day management with respect to the investments or strategies discussed.

Municipal Obligations. Municipal obligations include bonds, notes, floating-rate notes and commercial paper issued by a municipality, a group of municipalities or participants in qualified issues of municipal debt for a wide variety of both public and private purposes. Revenue bonds are payable only from the revenues derived from a particular facility or class of facilities or, in some cases, from the proceeds of a special excise tax or other specific revenue source such as payments from the user of the facility being financed. Municipal obligations also include municipal lease obligations and certificates of participations in municipal leases. A municipal lease obligation is a bond that is secured by lease payments made by the party, typically a state or municipality, leasing the facilities (e.g., schools or office buildings) that were financed by the bond. Such lease payments may be subject to annual appropriation or may be made only from revenues associated with the facility financed. In other cases, the leasing state or municipality is obligated to appropriate funds from its general tax revenues to make lease payments as long as it utilizes the leased property. A certificate of participation (also referred to as a “participation”) in a municipal lease is an instrument evidencing a pro rata share in a specific pledged revenue stream, usually lease payments by the issuer that are typically subject to annual appropriation. The certificate generally entitles the holder to receive a share, or participation, in the payments from a particular project.

Certain municipal obligations may be purchased on a “when-issued” basis, which means that payment and delivery occur on a future settlement date. The price and yield of such securities are generally fixed on the date of commitment to purchase.

The Fund may invest in zero coupon bonds, which do not make cash interest payments during a portion or all of the life of the bond. Instead, such bonds are sold at a deep discount to face value, and the interest consists of the gradual appreciation in price as the bond approaches maturity. Zero coupon bonds can be an attractive financing method for issuers with near-term cash-flow problems or seeking to preserve liquidity. Principal only investments entitle the Fund to receive the stated value of such investment when held to maturity.

Certain municipal obligations are issued with interest rates that adjust periodically. Such municipal floating-rate debt obligations are generally indexed to the Securities Industry and Financial Markets Association index, the Consumer Price Index or other indices. Municipal floating-rate debt obligations include, but are not limited to, municipal floating-rate notes, floating-rate notes issued by tender option bond trusts, auction rate preferred securities, synthetic floating-rate securities (e.g., a fixed-rate instrument that is subject to a swap agreement converting a fixed rate to a floating rate) and other municipal instruments with floating interest rates (such as variable rate demand preferred shares and variable rate term preferred shares).

The interest on tax-exempt municipal obligations is (in the opinion of the issuer’s counsel) exempt from regular federal income and state or local taxes, as applicable. Income from certain types of municipal obligations generally may be subject to the federal alternative minimum tax (the “AMT”) for individuals. Investors subject to AMT should consult their tax advisors.

Issuers of general obligation bonds include states, counties, cities, towns and regional districts. The proceeds of these obligations are used to fund a wide range of public projects, including the construction or improvement of schools, highways and roads, water and sewer systems and a variety of other public purposes. The basic security of general obligation bonds is the issuer’s pledge of its faith, credit, and taxing power for the payment of principal and interest. The taxes that can be levied for the payment of debt service may be limited or unlimited as to rate and amount. General obligation bonds issued by municipalities can be adversely affected by economic downturns and the resulting decline in tax revenues, pension funding risk, other post-employment benefit risk, budget imbalances, taxing ability risk, lack of political willpower and federal funding risk, among others. Revenue bonds can be adversely affected by the negative economic viability of the facility or revenue source. Many municipal obligations provide the issuer the option to “call,” or redeem, its securities. As such, the effective maturity of a municipal obligation may be reduced as the result of such call provisions and, if an investment is called in a declining interest rate environment, the proceeds from the called bond may have to be reinvested at a lower interest rate.

Calvert Responsible Municipal Income Fund9Prospectus dated May 1, 2024

The values of zero coupon bonds and principal only investments are subject to greater fluctuation in response to changes in market interest rates than municipal obligations that pay interest currently. The Fund is required to distribute to shareholders income imputed to any zero coupon bonds or principal only investments even though such income may not be received by the Fund as distributable cash. Such distributions could reduce the Fund’s reserve position and require it to sell securities and incur a gain or loss at a time it may not otherwise want to in order to provide the cash necessary for these distributions.

Credit Risk. Investments in debt instruments are subject to the risk of non-payment of scheduled principal and interest. Changes in economic conditions or other circumstances may reduce the capacity of the party obligated to make principal and interest payments on such instruments and may lead to defaults. Such non-payments and defaults may reduce the value of Fund shares and income distributions. The value of debt instruments also may decline because of concerns about the issuer’s ability to make principal and interest payments. In addition, the credit ratings of debt instruments may be lowered if the financial condition of the party obligated to make payments with respect to such instruments deteriorates. In the event of bankruptcy of the issuer of a debt instrument, the Fund could experience delays or limitations with respect to its ability to realize the benefits of any collateral securing the instrument. In order to enforce its rights in the event of a default, bankruptcy or similar situation, the Fund may be required to retain legal or similar counsel, which may increase the Fund’s operating expenses and adversely affect net asset value. See “Lower Rated Investments.” Municipal obligations may be insured as to principal and interest payments. If the claims-paying ability or other rating of the insurer is downgraded by a rating agency, the value of such obligations may be negatively affected. The Fund is also exposed to credit risk when it engages in certain types of derivatives transactions and when it engages in transactions that expose the Fund to counterparty risk. See “Derivatives.”

In evaluating the quality of a particular instrument, the investment adviser (or sub-adviser, if applicable) may take into consideration, among other things, a credit rating assigned by a credit rating agency, the issuer’s financial resources and operating history, its sensitivity to economic conditions and trends, the ability of its management, its debt maturity schedules and borrowing requirements, and relative values based on anticipated cash flow, interest and asset coverage, and earnings prospects. Credit rating agencies are private services that provide ratings of the credit quality of certain investments. Credit ratings issued by rating agencies are based on a number of factors including, but not limited to, the issuer’s financial condition and the rating agency’s credit analysis, if applicable, at the time of rating. As such, the rating assigned to any particular security is not necessarily a reflection of the issuer’s current financial condition. The ratings assigned are not absolute standards of credit quality and do not evaluate market risks or necessarily reflect the issuer’s current financial condition or the volatility or liquidity of the security.

For purposes of determining compliance with the Fund’s credit quality restrictions, if any, the Fund’s investment adviser (or sub-adviser, if applicable) relies primarily on the ratings assigned by credit rating agencies but may, in the case of unrated instruments, perform its own credit and investment analysis to determine an instrument’s credit quality. A credit rating may have a modifier (such as plus, minus or a numerical modifier) to denote its relative status within the rating. The presence of a modifier does not change the security credit rating (for example, BBB- and Baa3 are within the investment grade rating) for purposes of the Fund’s investment limitations. If an instrument is rated differently by two or more rating agencies, the highest rating will be used for any Fund rating restrictions.

Duration. Duration measures the time-weighted expected cash flows of a fixed-income security, while maturity refers to the amount of time until a fixed-income security matures. Duration differs from maturity in that it considers a security’s coupon payments in addition to the amount of time until the security matures. As the value of a security changes over time, so will its duration. Various techniques may be used to shorten or lengthen Fund duration.

Interest Rate Risk. In general, the value of income securities will fluctuate based on changes in interest rates. The value of these securities is likely to increase when interest rates fall and decline when interest rates rise. Generally, securities with longer durations or maturities are more sensitive to changes in interest rates than securities with shorter durations or maturities, causing them to be more volatile. Conversely, fixed-income securities with shorter durations or maturities will be less volatile but may provide lower returns than fixed-income securities with longer durations or maturities. In a rising interest rate environment, the duration of income securities that have the ability to be prepaid or called by the issuer may be extended. In a declining interest rate environment, the proceeds from prepaid or maturing instruments may have to be reinvested at a lower interest rate. Because the Fund is managed toward an income objective, it may hold more longer duration or maturity obligations and thereby be more exposed to interest rate risk than municipal income funds that are managed with a greater emphasis on total return. Certain factors, such as the presence of call features, may cause a particular fixed-income security, or the Fund as a whole, to exhibit less sensitivity to changes in interest rates. Certain of the Fund’s investments may also be valued, in part, by reference to the relative relationship between interest rates on tax-exempt securities and taxable securities, respectively. When the market for tax-exempt securities underperforms (or outperforms) the market for taxable securities, the value of these investments may be negatively affected (or positively affected). Certain countries and regulatory bodies may use negative interest rates as a monetary policy tool to encourage

Calvert Responsible Municipal Income Fund10Prospectus dated May 1, 2024

economic growth during periods of deflation. In a negative interest rate environment, debt instruments may trade at negative yields, which means the purchaser of the instrument may receive at maturity less than the total amount invested. Changes in governmental policy, including changes in central bank monetary policy, could cause interest rates to rise rapidly, or cause investors to expect a rapid rise in interest rates. This could lead to heightened levels of interest rate, volatility and liquidity risks for the fixed income markets generally and could have a substantial and immediate effect on the values of the Fund's investments.

LIBOR. The London Interbank Offered Rate or LIBOR was the average offered rate for various maturities of short-term loans between major international banks who were members of the British Bankers Association. It historically was used throughout global banking and financial industries to determine interest rates for a variety of financial instruments (such as debt instruments and derivatives) and borrowing arrangements. In July 2017, the Financial Conduct Authority (the “FCA”), the United Kingdom financial regulatory body, announced a desire to phase out the use of LIBOR. The ICE Benchmark Administration Limited, the administrator of LIBOR, ceased publishing certain LIBOR settings on December 31, 2021, and ceased publishing the remaining LIBOR settings on June 30, 2023. In addition, global regulators have announced that, with limited exceptions, no new LIBOR-based contracts should be entered into after 2021. Market participants have transitioned or are in the process of transitioning to the use of alternative reference or benchmark rates.

The impact of the transition away from LIBOR on certain debt securities, derivatives and other financial instruments that utilize LIBOR remains uncertain. The transition away from LIBOR and the use of replacement rates may adversely affect transactions that used LIBOR as a reference rate, financial institutions, funds and other market participants that engaged in such transactions, and the financial markets generally. The transition may result in changes in (i) the value of certain instruments held by the Fund, (ii) the cost of temporary borrowing for the Fund, or (iii) the effectiveness of related Fund transactions such as hedges, as applicable.

In planning for the transition away from LIBOR, various financial industry groups encountered obstacles to converting certain longer term securities and transactions to a new benchmark. In June 2017, the Alternative Reference Rates Committee, a group of large U.S. banks working with the Federal Reserve, announced its selection of a new Secured Overnight Financing Rate (“SOFR”), which is intended to be a broad measure of secured overnight U.S. Treasury repo rates, as an appropriate replacement for LIBOR. Bank working groups and regulators in other countries have suggested other alternatives for their markets, including the Sterling Overnight Interbank Average Rate (“SONIA”) in England. Both SOFR and SONIA, as well as certain other proposed replacement rates, are materially different from LIBOR, and changes in the applicable spread for financial instruments transitioning away from LIBOR need to be made to accommodate the differences. Liquid markets for newly-issued instruments that use an alternative reference rate are still developing. Consequently, there may be challenges for the Fund to enter into hedging transactions against instruments tied to alternative reference rates until a market for such hedging transactions develops.

Additionally, while many LIBOR-based instruments contemplated a scenario where LIBOR is no longer available by providing for an alternative or “fallback” rate-setting methodology, there may be significant uncertainty regarding the effectiveness of any such alternative methodologies to replicate LIBOR. Not all LIBOR-based instruments had such fallback provisions. Federal legislation has been enacted in the U.S. to assist with the transition away from LIBOR to new reference rates for instruments known as “tough legacy” contracts. Although there are ongoing efforts among global government entities and other organizations to address transition-related uncertainties, the ultimate effectiveness of such efforts is not yet known.

Any effects of the transition away from LIBOR and the adoption of alternative reference rates, as well as other unforeseen effects, could result in losses to the Fund. Furthermore, the risks associated with the discontinuation of LIBOR and transition to replacement rates may be exacerbated if an orderly transition to an alternative reference rate is not completed in a timely manner.

Lower Rated Investments. Investments in obligations rated below investment grade and comparable unrated securities (sometimes referred to as “junk”) generally entail greater economic, credit and liquidity risks than investment grade securities. Lower rated investments are speculative because of increased credit risk relative to other fixed income investments. Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments. An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs. Lower rated investments generally are subject to greater price volatility and illiquidity than higher rated investments. Lower rated investments are considered primarily speculative with respect to the issuer’s capacity to pay interest and repay principal.

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the risks of investing in lower rated or unrated securities through, among other things, active portfolio management, credit analysis and attention to current developments and trends in the economy and the financial markets, there can be no assurance that the investment adviser will be successful in doing so.

Derivatives. Generally, derivatives can be characterized as financial instruments whose performance is derived at least in part from the performance of an underlying reference instrument. Derivative instruments may be acquired in the United States or abroad consistent with the Fund’s investment strategy and may include the various types of exchange-traded and over-the-counter (“OTC”) instruments described herein and other instruments with substantially similar characteristics and risks. Fund obligations created pursuant to derivative instruments may give rise to leverage, which may subject the Fund to heightened risk of loss. The Fund may invest in a derivative transaction if it is permitted to own, invest in, or otherwise have economic exposure to the reference instrument. Depending on the type of derivative instrument and the Fund’s investment strategy, a reference instrument could be a security, instrument, index, currency, commodity, economic indicator or event (“reference instruments”). The Fund may purchase or sell futures contracts for hedging purposes. The Fund may also purchase or sell residual interest bonds.

Derivative instruments are subject to a number of risks, including adverse or unexpected movements in the price of the reference instrument, and counterparty, liquidity, market, tax and leverage risks. Certain derivatives may also be subject to credit risk and interest rate risk. In addition, derivatives also involve the risk that changes in their value may not correlate perfectly with the assets, rates, indices or instruments they are designed to hedge or closely track. Use of derivative instruments may cause the realization of higher amounts of short-term capital gains (generally taxed at ordinary income tax rates) than if such instruments had not been used. Success in using derivative instruments to hedge portfolio assets depends on the degree of price correlation between the derivative instruments and the hedged asset. Imperfect correlation may be caused by several factors, including temporary price disparities among the trading markets for the derivative instrument, the reference instrument and the Fund’s assets. To the extent that a derivative instrument is intended to hedge against an event that does not occur, the Fund may realize losses.

OTC derivative instruments involve an additional risk in that the issuer or counterparty may fail to perform its contractual obligations. Some derivative instruments are not readily marketable or may become illiquid under adverse market conditions. In addition, during periods of market volatility, an option or commodity exchange or swap execution facility or clearinghouse may suspend or limit trading in an exchange-traded derivative instrument, which may make the contract temporarily illiquid and difficult to price. Commodity exchanges may also establish daily limits on the amount that the price of a futures contract or futures option can vary from the previous day’s settlement price. Once the daily limit is reached, no trades may be made that day at a price beyond the limit. This may prevent the closing out of positions to limit losses. The ability to terminate OTC derivative instruments may depend on the cooperation of the counterparties to such contracts. For thinly traded derivative instruments, the only source of price quotations may be the selling dealer or counterparty. In addition, certain provisions of the Code limit the use of derivative instruments. Derivatives permit the Fund to increase or decrease the level of risk, or change the character of the risk, to which its portfolio is exposed in much the same way as the Fund can increase or decrease the level of risk, or change the character of the risk, of its portfolio by making investments in specific securities. There can be no assurance that the use of derivative instruments will benefit the Fund.

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contracts (“QFCs”) with counterparties that are part of U.S. or foreign global systemically important banking organizations be amended to include contractual restrictions on close-out and cross-default rights. QFCs include, but are not limited to, securities contracts, commodities contracts, forward contracts, repurchase agreements, securities lending agreements and swaps agreements, as well as related master agreements, security agreements, credit enhancements, and reimbursement obligations. If a covered counterparty of a Fund or certain of the covered counterparty’s affiliates were to become subject to certain insolvency proceedings, a Fund may be temporarily unable to exercise certain default rights, and the QFC may be transferred to another entity. In addition, under the rule, a Fund is permitted to invest in a security on a when-issued or forward-settling basis, or with a non-standard settlement cycle, and the transaction will be deemed not to involve a senior security under the 1940 Act, provided that (i) the Fund intends to physically settle the transaction and (ii) the transaction will settle within 35 days of its trade date (the “Delayed-Settlement Securities Provision”). A Fund may otherwise engage in such transactions that do not meet the conditions of the Delayed-Settlement Securities Provision so long as the Fund treats any such transaction as a “derivatives transaction” for purposes of compliance with the rule. Furthermore, under the rule, a Fund will be permitted to enter into an unfunded commitment agreement, and such unfunded commitment agreement will not be subject to the asset coverage requirements under the 1940 Act, if the Fund reasonably believes, at the time it enters into such agreement, that it will have sufficient cash and cash equivalents to meet its obligations with respect to all such agreements as they come due. These requirements may impact a Fund’s credit and counterparty risks.

Residual Interest Bonds. Residual interest bonds are issued by a trust (the “trust”) that holds municipal obligations. The value of residual interest bonds is derived from the value of such obligations. The trust also issues floating-rate notes to third parties that may be senior to the residual interest bonds. Residual interest bonds make interest payments to holders of the residual interest that bear an inverse relationship to the interest rate paid on the floating-rate notes. As required by applicable accounting standards, the Fund records interest expense as a liability with respect to floating-rate notes and also records offsetting interest income in an amount equal to this expense. While residual interest bonds create leverage, they do not constitute borrowings for purposes of the Fund’s restrictions on borrowings.

Futures Contracts. Futures are standardized, exchange-traded contracts. Futures contracts on securities obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of the financial instrument called for in the contract at a specified future date at a specified price. An index futures contract obligates the purchaser to take, and a seller to deliver, an amount of cash equal to a specific dollar amount times the difference between the value of a specific index at the close of the last trading day of the contract and the price at which the agreement is made. No physical delivery of the underlying securities in the index is made. It is the practice of holders of futures contracts to close out their positions on or before the expiration date by use of offsetting contract positions, and physical delivery of financial instruments or delivery of cash, as applicable, is thereby avoided. An option on a futures contract gives the holder the right to enter into a specified futures contract.

Interest Rate Swaps. Interest rate swaps involve the exchange by the Fund with another party of their respective commitments to pay or receive interest, e.g., an exchange of fixed rate payments for floating-rate payments.

Credit Default Swaps. Credit default swap agreements (“CDS”) enable the Fund to buy or sell credit protection on an individual issuer or basket of issuers (i.e., the reference instrument). The Fund may enter into CDS to gain or short exposure to a reference instrument. Long CDS positions are utilized to gain exposure to a reference instrument (similar to buying the instrument) and are akin to selling insurance on the instrument. Short CDS positions are utilized to short exposure to a reference instrument (similar to shorting the instrument) and are akin to buying insurance on the instrument.

Under a CDS, the protection “buyer” in a credit default contract is generally obligated to pay the protection “seller” an upfront or a periodic stream of payments over the term of the contract, provided that no credit event, such as a default, on a reference instrument has occurred. If a credit event occurs, the seller generally must pay the buyer the “par value” (full notional value) of the reference instrument in exchange for an equal face amount of the reference instrument described in the swap, or the seller may be required to deliver the related net cash amount, if the swap is cash settled. If the Fund is a buyer and no credit event occurs, the Fund may recover nothing if the swap is held through its termination date. As a seller, the Fund generally receives an upfront payment or a fixed rate of income throughout the term of the swap provided that there is no credit event. The Fund’s obligations under a CDS will be accrued daily (offset against any amounts owed to the Fund).

In response to market events, federal and certain state regulators have proposed regulation of the CDS market. These regulations may limit the Fund’s ability to use CDS and/or the benefits of CDS. CDS may be difficult to value and generally pay a return to the party that has paid the premium only in the event of an actual default by the issuer of the underlying obligation (as opposed to a credit downgrade or other indication of financial difficulty). The Fund may have difficulty, be unable or may incur additional costs to acquire any securities or instruments it is required to deliver under a CDS. The Fund may have limited ability to eliminate its exposure under a CDS either by assignment or other

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disposition, or by entering into an offsetting swap agreement. The Fund also may have limited ability to eliminate its exposure under a CDS if the reference instrument has declined in value.

Total Return Swaps. A total return swap is a contract in which one party agrees to make periodic payments to another party based on the change in market value of a reference instrument during the specified period, in return for periodic payments from the other party that are based on a fixed or variable interest rate or the total return of the reference instrument or another reference instrument. Total return swap agreements may be used to obtain exposure to a security or market without owning or taking physical custody of such security or investing directly in such market.

Credit Linked Notes. A credit linked note (“CLN”) is a type of hybrid instrument in which a special purpose entity issues a structured note (the “note issuer”) with respect to which the reference instrument is a single bond, a portfolio of bonds or the unsecured credit of an issuer, in general (each a “reference credit”). The purchaser of the CLN (the “note purchaser”) invests a par amount and receives a payment during the term of the CLN that equals a fixed or floating rate of interest equivalent to a high rated funded asset (such as a bank certificate of deposit) plus an additional premium that relates to taking on the credit risk of the reference credit. Upon maturity of the CLN, the note purchaser will receive a payment equal to: (i) the original par amount paid to the note issuer, if there is no occurrence of a designated event of default, restructuring or other credit event (each a “credit event”) with respect to the issuer of the reference credit; or (ii) the market value of the reference credit, if a credit event has occurred. Depending upon the terms of the CLN, it is also possible that the note purchaser may be required to take physical delivery of the reference credit in the event of a credit event. Most CLNs use a corporate bond (or a portfolio of corporate bonds) as the reference credit. However, almost any type of fixed-income security (including foreign government securities), index or derivative contract (such as a credit default swap) can be used as the reference credit.

Forward Rate Agreements. Under a forward rate agreement, the Fund locks in an interest rate at a future settlement date. If the interest rate on the settlement date exceeds the lock rate, the Fund pays the seller the difference between the two rates. If the lock rate exceeds the interest rate on the settlement date, the seller pays the Fund the difference between the two rates. Any such gain received by the Fund would be taxable. These instruments are traded in the OTC market.

U.S. Treasury and Government Securities. U.S. Treasury securities (“Treasury Securities”) include U.S. Treasury obligations that differ in their interest rates, maturities and times of issuance. U.S. Government agency securities (“Agency Securities”) include obligations issued or guaranteed by U.S. Government agencies or instrumentalities and government-sponsored enterprises. Agency Securities may be guaranteed by the U.S. Government or they may be backed by the right of the issuer to borrow from the U.S. Treasury, the discretionary authority of the U.S. Government to purchase the obligations, or the credit of the agency, instrumentality or enterprise.

Government-sponsored enterprises, such as the Federal Home Loan Mortgage Corporation (“Freddie Mac”), the Federal National Mortgage Association (“Fannie Mae”), the Federal Home Loan Banks (“FHLBs”), the Private Export Funding Corporation (“PEFCO”), the Federal Deposit Insurance Corporation (“FDIC”), the Federal Farm Credit Banks (“FFCB”) and the Tennessee Valley Authority (“TVA”), although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. Government. Because these securities are not backed by the full faith and credit of the United States, there is a risk that the U.S. Government will not provide financial support to these agencies if not obligated to do so by law. The maximum potential liability of the issuers of some U.S. government securities held by the Fund may greatly exceed their current resources, including their legal right to support from the U.S. Treasury. It is possible that these issuers will not have the funds to meet their payment obligations in the future. The interest from U.S. government securities generally is not subject to state and local taxation. Treasury Securities and Agency Securities also include any security or agreement collateralized or otherwise secured by Treasury Securities or Agency Securities, respectively.

Because of their high credit quality and market liquidity, U.S. Treasury and Agency Securities generally provide a lower current return than obligations of other issuers. While the U.S. Government has provided financial support to Fannie Mae and Freddie Mac in the past, there can be no assurance that it will support these or other government-sponsored enterprises in the future. In addition, uncertainty regarding the status of negotiations in the U.S. Government to increase the statutory debt ceiling could increase the risk that the U.S. Government may default on payments on certain U.S. government securities and may cause the credit rating of the U.S. Government to be downgraded. Any uncertainty regarding the ability of the United States to repay its debt obligations, and any default by the U.S. Government, would have a negative impact on the Fund’s investments in U.S. government securities.

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portion of the cost to register the securities. The Fund also may acquire securities through private placements under which it may agree to contractual restrictions on the resale of such securities that are in addition to applicable legal restrictions. In addition, if the investment adviser and/or sub-adviser, if applicable, receives non-public information about the issuer, the Fund may as a result be unable to sell the securities.

Restricted securities may be difficult to value properly and may involve greater risks than securities that are not subject to restrictions on resale. It may be difficult to sell restricted securities at a price representing fair value until such time as the securities may be sold publicly. Under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer, the Fund could find it more difficult to sell such securities when the investment adviser and/or sub-adviser, if applicable, believes it advisable to do so or may be able to sell such securities only at prices lower than if such securities were more widely held. Holdings of restricted securities may increase the level of Fund illiquidity if eligible buyers become uninterested in purchasing them. Restricted securities may involve a high degree of business and financial risk, which may result in substantial losses.

Borrowing. The Fund is permitted to borrow for temporary purposes (such as to satisfy redemption requests, to remain fully invested in anticipation of expected cash inflows and to settle transactions). Any borrowings by the Fund are subject to the requirements of the 1940 Act. Borrowings are also subject to the terms of any credit agreement between the Fund and lender(s). Fund borrowings may be equal to as much as 331/3% of the value of the Fund’s total assets (including such borrowings) less the Fund’s liabilities (other than borrowings). The Fund will not purchase additional investments while outstanding borrowings exceed 5% of the value of its total assets.

In addition, the Fund will be required to maintain a specified level of asset coverage with respect to all borrowings and may be required to sell some of its holdings to reduce debt and restore coverage at times when it may not be advantageous to do so. The rights of the lender to receive payments of interest and repayments of principal of any borrowings made by the Fund under a credit facility are senior to the rights of holders of shares with respect to the payment of dividends or upon liquidation. In the event of a default under a credit arrangement, the lenders may have the right to cause a liquidation of the collateral (i.e., sell Fund assets) and, if any such default is not cured, the lenders may be able to control the liquidation as well.

Cash and Money Market Instruments; Temporary Defensive Positions. The Fund may invest in cash or money market instruments, including high quality short-term instruments or an affiliated or unaffiliated investment company that invests in such instruments. During unusual market conditions, including for temporary defensive purposes, the Fund may invest up to 100% of its assets in cash or money market instruments, which may be inconsistent with its investment objective(s) and other policies, and as such, the Fund may not achieve its investment objective(s) during this period.

Money market instruments may be adversely affected by market and economic events, such as a sharp rise in prevailing short-term interest rates; adverse developments in the banking industry, which issues or guarantees many money market instruments; adverse economic, political or other developments affecting issuers of money market instruments; changes in the credit quality of issuers; and default by a counterparty.

Pooled Investment Vehicles. The Fund may invest in pooled investment vehicles to the extent permitted by the 1940 Act, and the rules, regulations and interpretations thereunder, which include investment companies (mutual funds and exchange-traded funds (“ETFs”)). Pooled investment vehicles are subject to the risks of investing in the underlying securities or other instruments that they own. The market for ETFs, which are generally traded on an exchange and may be traded at a premium or discount to net asset value, is affected by the demand for those securities, regardless of the value of such fund’s underlying securities. Additionally, natural or environmental disasters, widespread disease or other public health issues, war, acts of terrorism or other events could result in increased premiums or discounts to such fund’s net asset value. The Fund will indirectly bear its proportionate share of any management fees and other operating expenses paid by unaffiliated and certain affiliated pooled investment vehicles in which it invests. If such fees exceed 0.01% of the average net assets of the Fund, the costs associated with such investments will be reflected under Acquired Fund Fees and Expenses in the Fund’s Annual Fund Operating Expenses table(s) in its Fund Summary.

Liquidity Risk. The Fund is exposed to liquidity risk when trading volume, lack of a market maker, or legal restrictions impair the Fund’s ability to sell particular investments or close derivative positions at an advantageous market price. Trading opportunities are also more limited for securities and other instruments that are not widely held or are traded in less developed markets. These factors may make it more difficult to sell or buy a security at a favorable price or time. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. It also may be more difficult to value less liquid investments. These effects may be exacerbated during times of financial or political stress. Increased Fund redemption activity also may increase liquidity risk due to the need of the Fund to sell portfolio investments and may negatively impact Fund performance.

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The Fund will not acquire any illiquid investment if, immediately after the acquisition, the Fund will have invested more than 15% of its net assets in illiquid investments. Illiquid investments mean any investments that the Fund’s investment adviser and/or sub-adviser, as applicable, reasonably expect cannot be sold or disposed of in seven calendar days or less under then-current market conditions without the sale or disposition significantly changing the market value of the investment.

Leverage. Certain types of Fund transactions may give rise to economic leverage, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund.

The use of leverage may cause the Fund to maintain liquid assets or liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations. Leverage may cause the Fund’s share price to be more volatile than if it had not been leveraged, as certain types of leverage may exaggerate the effect of any increase or decrease in the value of the Fund’s portfolio securities. The loss on leveraged investments may substantially exceed the initial investment.

Securities Lending. The Fund may lend its portfolio securities to broker-dealers and other institutional borrowers. During the existence of a loan, the Fund will continue to receive the equivalent of the interest paid by the issuer on the securities loaned, or all or a portion of the interest on investment of the collateral, if any. The Fund may pay lending fees to such borrowers. Loans will only be made to firms that have been approved by the investment adviser, and the investment adviser or the securities lending agent will periodically monitor the financial condition of such firms while such loans are outstanding. Securities loans will only be made when the investment adviser believes that the expected returns, net of expenses, justify the attendant risks. Securities loans currently are required to be secured continuously by collateral in cash, cash equivalents (such as money market instruments) or other liquid securities held by the custodian and maintained in an amount at least equal to the market value of the securities loaned. The Fund may engage in securities lending to generate income. Upon return of the loaned securities, the Fund would be required to return the related collateral to the borrower and may be required to liquidate portfolio securities in order to do so. The Fund may lend up to one-third of the value of its total assets or such other amount as may be permitted by law.

As with other extensions of credit, there are risks of delay in recovery or even loss of rights in the securities loaned if the borrower of the securities fails financially. To the extent that the portfolio securities acquired with such collateral have decreased in value, it may result in the Fund realizing a loss at a time when it would not otherwise do so. As such, securities lending may introduce leverage into the Fund. The Fund also may incur losses if the returns on securities that it acquires with cash collateral are less than the applicable rebate rates paid to borrowers and related administrative costs.

Cybersecurity Risk. With the increased use of technologies by Fund service providers to conduct business, such as the Internet, the Fund is susceptible to operational, information security and related risks. The Fund relies on communications technology, systems, and networks to engage with clients, employees, accounts, shareholders, and service providers, and a cyber incident may inhibit the Fund’s ability to use these technologies. In general, cyber incidents can result from deliberate attacks or unintentional events. Cyber attacks include, but are not limited to, gaining unauthorized access to digital systems (e.g., through “hacking” or malicious software coding) for purposes of misappropriating assets or sensitive information, corrupting data, or causing operational disruption. Cyber attacks may also be carried out in a manner that does not require gaining unauthorized access, such as causing denial-of-service attacks on websites. A denial-of-service attack is an effort to make network services unavailable to intended users, which could cause shareholders to lose access to their electronic accounts, potentially indefinitely. Employees and service providers also may not be able to access electronic systems to perform critical duties for the Fund, such as trading and NAV calculation, during a denial-of-service attack. There is also the possibility for systems failures due to malfunctions, user error and misconduct by employees and agents, natural disasters, or other foreseeable and unforeseeable events.

Because technology is consistently changing, new ways to carry out cyber attacks are always developing. Therefore, there is a chance that some risks have not been identified or prepared for, or that an attack may not be detected, which puts limitations on the Fund's ability to plan for or respond to a cyber attack. Similar types of cybersecurity risks also are present for issuers of securities in which the Fund invests, which could have material adverse consequences for those issuers and result in a decline in the market price of their securities. Furthermore, as a result of cyber attacks, technological disruptions, malfunctions or failures, an exchange or market may close or suspend trading in specific securities or the entire market, which could prevent the Fund from, among other things, buying or selling the Fund or accurately pricing its securities. Like other funds and business enterprises, the Fund and its service providers have experienced, and will continue to experience, cyber incidents consistently. In addition to deliberate cyber attacks, unintentional cyber incidents can occur, such as the inadvertent release of confidential information by the Fund or its service providers.

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invests, may disrupt and otherwise adversely affect their business operations. This may result in financial losses to the Fund, impede Fund trading, interfere with the Fund’s ability to calculate its NAV, limit a shareholder’s ability to purchase or redeem shares of the Fund or cause violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, litigation costs, or additional compliance costs. While many of the Fund’s service providers have established business continuity plans and risk management systems intended to identify and mitigate cyber attacks, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified. The Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund and issuers in which the Fund invests. The Fund and its shareholders could be negatively impacted as a result.

Geopolitical Risk. The increasing interconnectivity between global economies and markets increases the likelihood that events or conditions in one country, region, sector, industry or market or, with respect to one company, may adversely impact issuers in a different country, region, sector, industry or market. For example, adverse developments in the banking or financial services sector could impact companies operating in various sectors or industries and adversely impact the Fund’s investments. Securities in the Fund’s portfolio may underperform due to inflation (or expectations for inflation), interest rates, global demand for particular products or resources, natural disasters, health emergencies (such as epidemics and pandemics), terrorism, regulatory events and governmental or quasi-governmental actions. The occurrence of global events similar to those in recent years, such as terrorist attacks around the world, natural disasters, health emergencies, social and political discord, war, banking or debt crises and downgrades, among others, may result in market volatility and may have long term effects on both the U.S. and global financial markets. Other financial, economic and other global market and social developments or disruptions may result in similar adverse circumstances, and it is difficult to predict when similar events affecting the U.S. or global financial markets may occur, the effects that such events may have and the duration of those effects (which may last for extended periods).

Such global events may negatively impact broad segments of businesses and populations, cause a significant negative impact on the performance of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price, and/or exacerbate pre-existing political, social and economic risks to the Fund. The Fund’s operations may be interrupted and any such event(s) could have a significant adverse impact on the value and risk profile of the Fund’s portfolio. There is a risk that you may lose money by investing in the Fund.

Recent Market Conditions. The outbreak of COVID-19 and efforts to contain its spread resulted in closing borders, enhanced health screenings, changes to healthcare service preparation and delivery, quarantines, cancellations, disruptions to supply chains and customer activity, as well as general concern and uncertainty. The impact of this coronavirus, and the effects of other infectious illness outbreaks, epidemics or pandemics, may be short term or may continue for an extended period of time. Health crises caused by outbreaks of disease may exacerbate other pre-existing political, social and economic risks and disrupt normal market conditions and operations. For example, a global pandemic or other widespread health crisis could cause substantial market volatility and exchange trading suspensions and closures. In addition, the increasing interconnectedness of markets around the world may result in many markets being affected by events or conditions in a single country or region or events affecting a single or small number of issuers. The coronavirus outbreak and public and private sector responses thereto led to large portions of the populations of many countries working from home for indefinite periods of time, temporary or permanent layoffs, disruptions in supply chains, and lack of availability of certain goods. The impact of such responses could adversely affect the information technology and operational systems upon which the Fund and the Fund’s service providers rely, and could otherwise disrupt the ability of the employees of the Fund’s service providers to perform critical tasks relating to the Fund. Any such impact could adversely affect the Fund’s performance, or the performance of the securities in which the Fund invests and may lead to losses on your investment in the Fund.

General. The Fund's Tax-Exempt 80% Policy may only be changed with shareholder approval. Unless otherwise stated, the Fund's investment objective and certain other policies may be changed without shareholder approval. Shareholders will receive 60 days' advance written notice of any material change in the investment objective. The Fund might not use all of the strategies and techniques or invest in all of the types of securities described in this Prospectus or the SAI. While at times the Fund may use alternative investment strategies in an effort to limit its losses, it may choose not to do so.

Calvert Responsible Municipal Income Fund17Prospectus dated May 1, 2024

use of technologies by Fund service providers, such as the Internet, to conduct business, the Fund is susceptible to operational, information security and related risks. See “Additional Information about Investment Strategies and Risks” in the Fund’s SAI. In addition, it is expected that confidential or material non-public information regarding an investment or potential investment opportunity may become available to the investment adviser. If such information becomes available, the investment adviser may be precluded (including by applicable law or internal policies or procedures) from pursuing an investment or disposition opportunity with respect to such investment or investment opportunity and the investment adviser may be restricted in its ability to cause the Fund to buy or sell securities of an issuer for substantial periods of time when the Fund otherwise could realize profit or avoid loss. This may adversely affect the Fund's flexibility with respect to buying or selling securities and may impair the Fund's liquidity.

About Responsible Investing

Investment Selection Process

CRM seeks to invest in issuers that manage ESG risk exposures adequately and that are not exposed to excessive ESG risk through their principal business activities. Issuers are analyzed using The Calvert Principles for Responsible Investment (the “Calvert Principles”) (included as Appendix A to this Prospectus), a framework for considering ESG factors. Each issuer is evaluated relative to an appropriate peer group based on financially material ESG factors as determined by CRM. CRM’s evaluation of a particular security’s responsible investing characteristics generally involves both quantitative and qualitative analysis. In assessing investments, CRM generally focuses on the ESG factors relevant to the issuer’s operations, and an issuer may be acceptable for investment based primarily on such assessment. Securities may be deemed suitable for investment even if the issuer does not operate in accordance with all elements of the Fund’s responsible investing criteria. The Fund may also invest in issuers that CRM believes are likely to operate in accordance with the Calvert Principles pending CRM’s engagement activity with such issuer. In assessing issuers for which quantitative data is limited, subjective judgments may serve as the primary basis for CRM’s evaluation. The responsible investment criteria of the Fund may be changed by the Board without shareholder approval.

The Fund may invest in a fixed or floating-rate income security before CRM has completed its evaluation of the security’s responsible investment characteristics if, in the opinion of the portfolio manager, the timing of the purchase is appropriate given market conditions. Factors that a portfolio manager may consider in making such an investment decision include, but are not limited to, (i) prevailing market prices, (ii) liquidity, (iii) bid-ask spreads, (iv) market color, and (v) availability. Following any such investment in a security, CRM will evaluate the issuer to determine if it operates in a manner that is consistent with the Fund’s responsible investment criteria. If CRM determines that the issuer does not operate in a manner consistent with the Fund’s responsible investment criteria, the security will be sold in accordance with CRM’s guidelines, at a time and in a manner that is determined to be in the best interests of shareholders. If a security is sold prior to CRM’s responsible investment determination and is no longer held by the Fund, CRM may not complete its evaluation of such security.

As described above, or in the SAI, the Fund may invest in cash, money market instruments and ETFs. Such investments will generally not be subject to responsible investment analysis and will not be required to be consistent with the responsible investment criteria otherwise applicable to investments made by the Fund. In addition, ETFs in which the Fund may invest may hold securities of issuers that do not operate in accordance with the Fund’s responsible investment criteria. The foregoing investments will not be counted toward the Fund's policy of investing at least 80% of its net assets in issuers that the investment adviser determines operate in a manner consistent with or promote the Principles.

High Social Impact Investments. Up to 3% of the Fund's net assets may be invested in High Social Impact Investments. High Social Impact Investments are investments that, in the Adviser’s opinion, offer the opportunity for significant sustainability and social impact. High Social Impact Investments include (i) debt obligations that offer a below-market interest rate and (ii) equity investments that may not generate a market rate of return.

High Social Impact Investment debt obligations are unrated and of below-investment grade quality, and involve a greater risk of default and price decline than investment grade investments. High Social Impact Investments are illiquid, and the Fund may be unable to dispose of them at current carrying values.

Any Fund investment in High Social Impact Investments is fair valued pursuant to valuation procedures adopted by the Fund’s Board and implemented by the Adviser. See “Valuing Shares” in this Prospectus. High Social Impact Investments by the Fund may be direct investments in an issuer or investments in an intermediate entity that then makes High Social Impact Investments, such as Calvert Impact Capital, Inc. (“CIC”) (as discussed below).

Calvert Responsible Municipal Income Fund18Prospectus dated May 1, 2024

communities and sustain our planet. CIC issues Notes with fixed-rates of interest to domestic individuals and institutional investors and the proceeds from the Notes primarily are used to provide financing to community development organizations, projects, funds and other social enterprises across a variety of impact sectors, including community development, microfinance, affordable housing, small business, renewable energy, environmental sustainability, education, health, and sustainable agriculture (collectively, the “Participating Borrowers”) with missions that may include addressing climate change, supporting quality education, promoting financial inclusion, strengthening women’s empowerment, and increasing access to quality affordable housing. CIC issues Notes with fixed interest rates determined at the time of issuance and terms currently ranging from six months to 20 years, and in turn makes loans to Participating Borrowers at rates determined through consideration of the general current market, the Participating Borrower’s positive social and/or environmental impact and the Participating Borrower’s risk level.

The Adviser has licensed use of the Calvert name to CIC and provides other types of support. An officer of the Adviser serves on the CIC Board.

Management and Organization

Management. The Fund’s investment adviser is Calvert Research and Management (“CRM”). CRM is an indirect wholly owned subsidiary of Morgan Stanley. CRM, a registered investment adviser, has offices at 2050 M Street NW, Washington, DC 20036.

Morgan Stanley (NYSE: MS), whose principal offices are at 1585 Broadway, New York, New York 10036, is a preeminent global financial services firm engaged in securities trading and brokerage activities, as well as providing investment banking, research and analysis, financing and financial advisory services. As of March 31, 2024, Morgan Stanley’s asset management operations had aggregate assets under management of approximately $1.5 trillion.

The Fund’s semiannual shareholder report covering the fiscal period ended June 30 provides information regarding the basis for the Trustees’ approval of the Fund’s investment advisory agreement.

Under its investment advisory agreement with the Fund, CRM receives a monthly advisory fee equal to 0.35% annually of the Fund’s average daily net assets. For the fiscal year ended December 31, 2023, the effective annual rate of advisory fee paid was 0.35% of average daily net assets.

The portfolio managers of the Fund are Cynthia J. Clemson (since December 2016) and William J. Delahunty, Jr. (since October 2021). Ms. Clemson and Mr. Delahunty are Managing Directors of Morgan Stanley and Vice Presidents of CRM and have been employees of the Eaton Vance organization for more than five years. Ms. Clemson and Mr. Delahunty also manage other funds and portfolios.

The SAI provides additional information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of Fund shares.

CRM serves as the administrator of the Fund, providing the Fund with administrative services and related office facilities. The annual administrative fee is 0.12% of average daily net assets. For the fiscal year ended December 31, 2023, the administrative fees paid by the Fund (as a percentage of daily net assets) were 0.12% for each share class.

Eaton Vance Management (“Eaton Vance”) provides sub-transfer agency and related services to Calvert mutual funds pursuant to a Sub-Transfer Agency Support Services Agreement. For its services under the agreement, Eaton Vance receives an aggregate fee from such funds equal to its actual expenses incurred in performing such services.

Organization. The Fund is a series of Calvert Management Series, a Massachusetts business trust. The Fund offers multiple classes of shares. Each Class represents a pro rata interest in the Fund but is subject to different expenses and rights. The Fund does not hold annual shareholder meetings but may hold special meetings for matters that require shareholder approval (such as electing or removing Trustees, approving management or advisory contracts or changing investment policies that may only be changed with shareholder approval).

Valuing Shares

You may buy or sell (redeem) shares of the Fund at the NAV next determined for the class after receipt of your order in good order, plus any applicable sales charge. The Fund’s NAV is determined as of the close of the New York Stock Exchange (“NYSE”) (normally 4:00 p.m. Eastern Time) on each day that the NYSE is open for business (typically Monday through Friday) (the “Pricing Time”). The Fund is closed for business and will not issue a NAV on the following business holidays and any other business day that the NYSE is closed: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. On holidays or other days when the NYSE is closed, the NAV is generally not calculated and the Fund generally does not transact purchase or redemption requests. However, on those days, the value of the Fund’s assets may be affected to the extent that the Fund holds foreign securities that trade on foreign markets that are open. In

Calvert Responsible Municipal Income Fund19Prospectus dated May 1, 2024

addition, trading of securities that are primarily listed on foreign exchanges may take place on weekends and other days when the Fund does not price its interests or transact purchase or redemption requests.

If the NYSE is closed due to inclement weather, technology problems or any other reason on a day it would normally be open for business, or the NYSE has an unscheduled early closing on a day it has opened for business, the Fund reserves the right to treat such day as a business day and accept purchase and redemption orders until, and calculate its NAV as of, the normally scheduled close of regular trading on the NYSE for that day, so long as its investment adviser believes there generally remains an adequate market to obtain reliable and accurate market quotations. If market quotations, official closing prices, or information furnished by a pricing service are not readily available or, in the investment adviser’s opinion, are deemed unreliable for a security, then that security will be fair valued in good faith by the investment adviser in accordance with applicable fair value pricing policies and in accordance with applicable law. The Fund may elect to remain open and price its shares on days when the NYSE is closed but the primary securities markets on which the Fund’s securities trade remain open. To the extent, if any, that the Fund invests in securities primarily listed on foreign exchanges, the value of the Fund’s portfolio securities may change on days when you will not be able to purchase or sell your shares. When purchasing or redeeming Fund shares through a financial intermediary, your financial intermediary must receive your order by the close of regular trading on the NYSE in order for the purchase price or the redemption price to be based on that day’s net asset value per share. It is the financial intermediary’s responsibility to transmit orders promptly. The Fund may accept purchase and redemption orders as of the time of their receipt by certain financial intermediaries (or their designated intermediaries).

The Board has adopted procedures for valuing investments (the “Procedures”) and has delegated to the investment adviser, as valuation designee, the daily valuation of such investments. Pursuant to the Procedures, securities and other investments held by the Fund for which market quotations are readily available are generally valued at market value. Exchange-listed investments (including certain derivatives) are normally valued at last sale or closing prices. Exchange-traded options are valued at the mean of the bid and asked prices at valuation time as reported by the Options Price Reporting Authority for U.S. listed options, or by the relevant exchange or board of trade for non-U.S. listed options. Non-exchange traded derivatives are normally valued on the basis of quotes obtained from brokers and dealers or independent pricing services. Most loans and other debt obligations are valued using prices supplied by one or more pricing services.

Purchasing Shares

Set forth below is information about the manner in which the Fund offers shares. A financial intermediary may offer Fund shares subject to variations in or elimination of the Fund sales charges (“variations”), provided such variations are described in this Prospectus. All variations described in Appendix B are applied by, and the responsibility of, the identified financial intermediary. Sales charge variations may apply to purchases, sales, exchanges and reinvestments of Fund shares and a shareholder transacting in Fund shares through an intermediary identified on Appendix B should read the terms and conditions of Appendix B carefully. See also “Shareholder Account Features – ‘Street Name’ Accounts.” For the variations applicable to shares offered through certain financial intermediaries, please see Appendix B – Financial Intermediary Sales Charge Variations. A variation that is specific to a particular financial intermediary is not applicable to shares held directly with the Fund or through another intermediary.

You may purchase shares through your financial intermediary or by mailing an account application form to the transfer agent (see back cover for address). Purchase orders will be executed at the net asset value (plus any applicable sales charge) next determined after their receipt in proper form (meaning that the order is complete and contains all necessary information) by the Fund’s transfer agent. The Fund’s transfer agent or your financial intermediary must receive your purchase in proper form no later than the close of regular trading on the NYSE (normally 4:00 p.m. Eastern Time) for your

Calvert Responsible Municipal Income Fund20Prospectus dated May 1, 2024

purchase to be effected at that day’s net asset value. If you purchase shares through a financial intermediary, that intermediary may charge you a fee for executing the purchase for you.

The Fund may suspend the sale of its shares at any time and any purchase order may be refused for any reason. The U.S. registered Calvert funds generally do not accept investments from residents of the European Union, the United Kingdom or Switzerland. The Calvert funds also do not accept investments from other non-U.S. residents, provided that a fund may accept investments from certain non-U.S. investors at the discretion of the principal underwriter. The Fund does not issue share certificates.

As used throughout this Prospectus, the term “employer sponsored retirement plan” includes the following: an employer sponsored pension or profit sharing plan that qualifies under section 401(a) of the Code (such as a 401(k) plan, money purchase pension, profit sharing and defined benefit plan); ERISA covered 403(b) plan; Taft-Hartley multi-employer plan; and non-qualified deferred compensation arrangements that operate in a similar manner to a qualified retirement plan (including 457 plans and executive deferred compensation arrangements). Individual Retirement Accounts (“IRAs”) are not employer sponsored retirement plans for purposes of this definition.

Class A and Class C Shares

Your initial investment must be at least $1,000. After your initial investment, additional investments may be made in any amount at any time by sending a check payable to the order of the Fund or the transfer agent directly to the transfer agent (see back cover for address). Please include your name and account number and the name of the Fund and Class of shares with each investment. The Fund no longer accepts direct purchases of Class C shares by accounts for which no broker-dealer or other financial intermediary is specified. Any direct purchase received by the Fund's transfer agent for Class C shares for such accounts will automatically be invested in Class A shares.

The minimum initial investment amount and Fund policy of redeeming accounts with low account balances are waived for bank automated investing accounts, certain group purchase plans (including proprietary fee-based programs sponsored by financial intermediaries) and for persons affiliated with CRM, its affiliates and certain Fund service providers (as described in the SAI).

Class I Shares

Your initial investment must be at least $1,000,000, except as noted below. Class I shares are offered to clients of financial intermediaries who (i) charge such clients an ongoing fee for advisory, investment, consulting or similar services, or (ii) have entered into an agreement with the principal underwriter to offer Class I shares through a no-load network or platform. Such clients may include individuals, corporations, endowments, foundations and employer sponsored retirement plans. Class I shares may also be available through brokerage platforms of broker-dealer firms that have agreements with the Fund’s principal underwriter to offer Class I shares solely when acting as an agent for the investor. An investor acquiring Class I shares through such platforms may be required to pay a commission and/or other forms of compensation to the broker. The Fund offers other share classes that have different fees and expenses. Class I shares also are offered to investment and institutional clients of CRM and its affiliates and certain persons affiliated with CRM.

The Class I minimum initial investment is waived for persons affiliated with CRM, its affiliates and certain Fund service providers (as described in the SAI). The minimum initial investment also is waived for: (i) permitted exchanges; (ii) employer sponsored retirement plans; (iii) corporations, endowments and foundations with assets of at least $100 million; (iv) Class I shares purchased through the brokerage platforms described above; and (v) accounts of clients of financial intermediaries who (a) charge an ongoing fee for advisory, investment, consulting or similar services, or (b) have entered into an agreement with the principal underwriter to offer Class I shares through a no-load network or platform (in each case, as described above).

Class I shares may be purchased through a financial intermediary or by requesting your bank to transmit immediately available funds (Federal Funds) by wire. To make an initial investment by wire, you must complete an account application and telephone Calvert Shareholder Services at 1-800-368-2745 to be assigned an account number. You may request an account application by calling 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time). Shareholder Services must be advised by telephone of each additional investment by wire.

Subsequent Investments. Subsequent investments of any amount may be made at any time, including through automatic investment each month or quarter from your bank account. You may make automatic investments of $50 or more each month or each quarter from your bank account provided such investments equal a minimum of $200 per year. You can establish bank automated investing on the account application or by providing written instructions to the Fund’s transfer agent. Please call 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time) for further information.

Calvert Responsible Municipal Income Fund21Prospectus dated May 1, 2024

You also may make additional investments by accessing your account via the Calvert website at www.calvert.com. The trade date of purchases made through the Internet from a pre-designated bank account will be the day the purchase is requested through the Calvert website (provided the request is on a business day and submitted no later than the close of regular trading on the NYSE). For more information about purchasing shares through the Internet, please call 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time).

Inactive Accounts and Risk of Escheatment. In accordance with state “unclaimed property” laws, your Fund shares may legally be considered abandoned and required to be transferred to the relevant state (also known as “escheatment”) under various circumstances. These circumstances, which vary by state, can include inactivity (e.g., no owner-initiated contact for a certain period), returned mail (e.g., when mail sent to a shareholder is returned by the post office as undeliverable), uncashed checks or a combination of these. An incorrect address may cause a shareholder’s account statements and other mailings to be returned to the Fund or your financial intermediary. Since states’ statutory requirements regarding inactivity differ, it is important to regularly contact your financial intermediary or the Fund’s transfer agent. The process described above, and the application of state escheatment laws, may vary by state and/or depending on how shareholders hold their shares in the Fund.

It is your responsibility to ensure that you maintain a valid mailing address for your account, keep your account active by contacting your financial intermediary or the Fund’s transfer agent (e.g., by mail or telephone), and promptly cash all checks for dividends, capital gains and redemptions. Neither the Fund nor the investment adviser(s) will be liable to shareholders or their representatives for good faith compliance with escheatment laws.

For more information, please see https://www.calvert.com/mutual-funds-and-abandoned-property.php or please contact us at 1-800-368-2745.

Restrictions on Excessive Trading and Market Timing. The Fund is not intended for excessive trading or market timing. Market timers seek to profit by rapidly switching money into a fund when they expect the share price of the fund to rise and taking money out of the fund when they expect those prices to fall. By realizing profits through short-term trading, shareholders that engage in rapid purchases and sales (including exchanges, if permitted) of a fund’s shares may dilute the value of shares held by long-term shareholders. Volatility resulting from excessive purchases and sales of fund shares, especially involving large dollar amounts, may disrupt efficient portfolio management. In particular, excessive purchases and sales of a fund’s shares may cause a fund to have difficulty implementing its investment strategies, may force the fund to sell portfolio securities at inopportune times to raise cash or may cause increased expenses (such as increased brokerage costs, realization of taxable capital gains without attaining any investment advantage or increased administrative costs).

A fund that invests all or a portion of its assets in foreign securities may be susceptible to a time zone arbitrage strategy in which shareholders attempt to take advantage of fund share prices that may not reflect developments in a foreign securities market that occur after the close of such market but prior to the pricing of fund shares. In addition, a fund that invests in securities that are, among other things, thinly traded, traded infrequently or illiquid, is susceptible to the risk that the current market price for such securities may not accurately reflect current market values. A shareholder may seek to engage in short-term trading to take advantage of these pricing differences (commonly referred to as “price arbitrage”). The investment adviser is authorized to use the fair value of a security if prices are unavailable or are deemed unreliable (see “Valuing Shares”). The use of fair value pricing and the restrictions on excessive trading and market timing described below are intended to reduce a shareholder’s ability to engage in price or time zone arbitrage to the detriment of the Fund.

The Boards of the Calvert funds have adopted policies to discourage short-term trading and market timing and to seek to minimize their potentially detrimental effects (the “Policy”). Under the Policy, the Board has delegated to Eaton Vance, acting in its capacity as the Fund’s sub-transfer agent, the responsibility to reject or cancel a purchase order, suspend or terminate an exchange privilege or terminate the ability of a shareholder to invest in the Calvert funds if Eaton Vance determines that a proposed transaction involves market timing or excessive trading that it believes is likely to be detrimental to the Fund.

Calvert Responsible Municipal Income Fund22Prospectus dated May 1, 2024

all such cases. Eaton Vance may also reject or cancel any purchase order (including an exchange) from a shareholder or group of shareholders for any other reason. In applying the Policy, and in particular when determining whether a transaction is likely to be detrimental to a Fund, Eaton Vance will be required to make judgments that are inherently subjective and will depend on the specific facts and circumstances. Such determinations will be made in a manner believed to be in the best interest of the Fund’s shareholders. No Calvert fund has any arrangement to permit market timing.

The following Fund share transactions generally are exempt from the Policy because they generally do not raise market timing or excessive trading concerns:

·transactions (i) made pursuant to the Fund’s systematic purchase, exchange or redemption plan, (ii) made as the result of automatic reinvestment of dividends or distributions, or (iii) initiated by the Fund (e.g., for transactions due to a failure to meet applicable account minimums);

·transactions made by participants in employer sponsored retirement plans involving (i) participant payroll or employer contributions or loan repayments, (ii) redemptions as part of plan terminations or at the direction of the plan, mandatory retirement distributions, or (iii) rollovers;

·transactions in shares of Calvert Ultra-Short Duration Income Fund; or

·investments in a fund by ReFlow in connection with the ReFlow liquidity program (if applicable to the Fund, the ReFlow liquidity program is described under “Investment Objectives & Principal Policies and Risks” above).

The following Fund share transactions generally are exempt from the Limitation; however, these transactions are subject to monitoring by Eaton Vance and may be subject to restrictions if deemed likely to be detrimental to the Fund:

·transactions made by model-based discretionary advisory accounts; or

·transactions made by funds that invest in the Fund as part of an asset reallocation in accordance with their investment policies or in response to Fund inflows and outflows.

It may be difficult for Eaton Vance to identify market timing or excessive trading in omnibus accounts traded through financial intermediaries. Eaton Vance has provided guidance to financial intermediaries (such as banks, broker-dealers, insurance companies and retirement administrators) concerning the application of the Policy to Fund shares held in omnibus accounts maintained and administered by such intermediaries, including guidance concerning situations where market timing or excessive trading is considered to be detrimental to the Fund. Eaton Vance may rely on a financial intermediary’s policy to restrict market timing and excessive trading if it believes that policy is likely to prevent market timing that is likely to be detrimental to the Fund. Such policy may be more or less restrictive than the Policy. Although Eaton Vance reviews trading activity at the omnibus account level for activity that indicates potential market timing or excessive trading activity, Eaton Vance typically will not request or receive individual account data unless suspicious trading activity is identified. Eaton Vance generally relies on financial intermediaries to monitor trading activity in omnibus accounts in good faith in accordance with their own policies or the Policy. Eaton Vance cannot ensure that these financial intermediaries will in all cases apply the Policy or their own policies, as the case may be, to accounts under their control.

Choosing a Share Class. The Fund offers different classes of shares. The different classes of shares represent investments in the same portfolio of securities, but the classes are subject to different expenses and privileges, and will likely have different share prices due to differences in class expenses. A share class also may be subject to a sales charge. In choosing the class of shares that suits your investment needs, you should consider:

·how long you expect to own your shares;

·how much you intend to invest; and

·the total operating expenses associated with owning each class.

Each investor’s considerations are different. You should speak with your financial intermediary to help you decide which class of shares to purchase. Set forth below is a brief description of each class of shares offered by the Fund.

Class A shares are offered at net asset value plus a front-end sales charge of up to 3.25%. This charge is deducted from the amount you invest. The Class A sales charge is reduced for purchases of $100,000 or more. The sales charge applicable to your purchase may be reduced under the right of accumulation or a statement of intention, which are described in “Reducing or Eliminating Class A Sales Charges” under “Sales Charges” below. Some investors may be eligible to purchase Class A shares at net asset value under certain circumstances, which are also described below. Class A shares pay distribution and service fees equal to 0.25% annually of average daily net assets.

Calvert Responsible Municipal Income Fund23Prospectus dated May 1, 2024

Waivers” under “Sales Charges” below. Class C shares pay distribution and service fees equal to 1.00% annually of average daily net assets. Orders for Class C shares of one or more Calvert funds will be refused when the total value of the purchase (including the aggregate market value of all Calvert fund shares held within the purchasing shareholder’s account(s)) is $1 million or more. Investors considering cumulative purchases of $500,000 or more should consider whether another Class of shares would be more appropriate and consult their financial intermediary. The Fund no longer accepts direct purchases of Class C shares by accounts for which no broker-dealer or other financial intermediary is specified. Any direct purchase received by the Fund’s transfer agent for Class C shares for such accounts will automatically be invested in Class A shares. In addition, Class C shares held in an account for which no financial intermediary is specified and which are not subject to a CDSC will periodically be converted to Class A shares.

Class I shares are offered to clients of financial intermediaries who (i) charge such clients an ongoing fee for advisory, investment, consulting or similar services, or (ii) have entered into an agreement with the principal underwriter to offer Class I shares through a no-load network or platform. Such clients may include individuals, corporations, endowments, foundations and employer sponsored retirement plans. Class I shares may also be available through brokerage platforms of broker-dealer firms that have agreements with the Fund’s principal underwriter to offer Class I shares solely when acting as an agent for the investor. An investor acquiring Class I shares through such platforms may be required to pay a commission and/or other forms of compensation to the broker. Class I shares are also offered to investment and institutional clients of CRM and its affiliates, and certain persons affiliated with CRM (including employees, officers and directors of CRM’s affiliates). Class I shares do not pay distribution or service fees.

Payments to Financial Intermediaries. In addition to payments disclosed under “Sales Charges” below, the principal underwriter, out of its own resources, may make cash payments to certain financial intermediaries (which may include affiliates of the principal underwriter and investment adviser) who provide marketing support, transaction processing and/or administrative services and, in some cases, include some or all Calvert funds in preferred or specialized selling programs. Payments made by the principal underwriter to a financial intermediary may be significant and are typically in the form of fees based on Fund sales, assets, transactions processed and/or accounts attributable to that financial intermediary. Financial intermediaries also may receive amounts from the principal underwriter in connection with educational or due diligence meetings that include information concerning Calvert funds. The principal underwriter may pay or allow other promotional incentives or payments to financial intermediaries to the extent permitted by applicable laws and regulations.

Certain financial intermediaries that maintain fund accounts for the benefit of their customers provide sub-accounting, recordkeeping and/or administrative services to the Calvert funds and are compensated for such services by the funds. As used in this Prospectus, the term “financial intermediary” includes any broker, dealer, bank (including bank trust departments), registered investment adviser, financial planner, a retirement plan and/or its administrator, their designated intermediaries and any other firm having a selling, administration or similar agreement with the principal underwriter or its affiliates.

Sales Charges

Class A Front-End Sales Charge. Class A shares are offered at net asset value per share plus a sales charge that is determined by the amount of your investment. The current sales charge schedule is:

Amount of Purchase	Sales Charge* as a Percentage of Offering Price	Sales Charge* as a Percentage of Net Amount Invested	Dealer Commission as a Percentage of Offering Price
Less than $100,000	3.25%	3.36%	2.75%
$100,000 but less than $250,000	2.00%	2.04%	1.50%
$250,000 but less than $500,000	1.00%	1.01%	0.50%
$500,000 or more	0.00**	0.00**	TIERED**

*Because the offering price per share, which includes the front-end sales charge, is rounded to two decimal places, the actual sales charge you pay on a purchase of Class A shares may be more or less than your total purchase amount multiplied by the applicable sales charge percentage.

**No sales charge is payable at the time of purchase on investments of $500,000 or more. The principal underwriter will pay a commission to financial intermediaries on sales of $500,000 or more as follows: 0.75% on amounts of $500,000 or more but less than $4 million; plus 0.50% on amounts of $4 million but less than $15 million; plus 0.25% on amounts of $15 million or more. A CDSC of 0.75% will be imposed on such investments (as described below) in the event of redemptions within 12 months of purchase.

Calvert Responsible Municipal Income Fund24Prospectus dated May 1, 2024

Reducing or Eliminating Class A Sales Charges. Front-end sales charges on purchases of Class A shares may be reduced under the right of accumulation or under a statement of intention. To receive a reduced sales charge, you must inform your financial intermediary or the Fund at the time you purchase shares that you qualify for such a reduction. If you do not let your financial intermediary or the Fund know you are eligible for a reduced sales charge at the time of purchase, you will not receive the discount to which you may otherwise be entitled.

Right of Accumulation. Under the right of accumulation, the sales charge you pay is reduced if the current market value of your holdings in the Fund or any other Calvert fund (based on the current maximum public offering price) plus your new purchase total is $100,000 or more. Shares owned by you, your spouse and children under age twenty-one may be combined for purposes of the right of accumulation, including shares held for the benefit of any of you in omnibus or “street name” accounts. In addition, shares held in a trust or fiduciary account of which any of the foregoing persons is the sole beneficiary (including employer sponsored retirement plans and IRAs) may be combined for purposes of the right of accumulation. Shares purchased and/or owned in a SEP, SARSEP and SIMPLE IRA plan may be combined for purposes of the right of accumulation for the plan and its participants. You may be required to provide documentation to establish your ownership of shares included under the right of accumulation (such as account statements for you, your spouse and children or marriage certificates, birth certificates and/or trust or other fiduciary-related documents).

Statement of Intention. Under a statement of intention, purchases of $100,000 or more made over a 13-month period are eligible for reduced sales charges. Shares eligible under the right of accumulation (other than those included in employer sponsored retirement plans) may be included to satisfy the amount to be purchased under a statement of intention. Under a statement of intention, the principal underwriter may hold 5% of the dollar amount to be purchased in escrow in the form of shares registered in your name until you satisfy the statement or the 13-month period expires. A statement of intention does not obligate you to purchase (or the Fund to sell) the full amount indicated in the statement. If during the 13-month period you redeem any of the shares that you purchased pursuant to the statement of intention, the value of the redeemed shares will not be included for purposes of satisfying your statement of intention. For additional information about statements of intention, see “Sales Charges” in the SAI.

Class A shares are offered at net asset value (without a sales charge) to accounts of clients of financial intermediaries who (i) charge an ongoing fee for advisory, investment, consulting or similar services, or (ii) have entered into an agreement with the principal underwriter to offer Class A shares through a no-load network or platform, or self-directed brokerage accounts that may or may not charge transaction fees to customers; or (iii) employer sponsored retirement plans. Class A shares also are offered at net asset value to investment and institutional clients of CRM and its affiliates; certain persons affiliated with CRM; direct purchases of shares by accounts where no financial intermediary is specified; and to certain fund service providers as described in the SAI. Class A shares are also offered at net asset value to shareholders who make a permitted direct transfer or roll-over to a Calvert prototype IRA from an employer-sponsored retirement plan previously invested in Calvert funds (applicable only to the portion previously invested in Calvert funds), provided that sufficient documentation is provided to the transfer agent of such transfer or roll-over at the time of the account opening. Class A shares may also be purchased at net asset value pursuant to the exchange privilege and when distributions are reinvested. A financial intermediary may not, in accordance with its policies and procedures, offer one or more of the waiver categories described above and shareholders should consult their financial intermediary for more information. The Fund may eliminate, modify or add to the terms of these sales charge waivers at any time without providing notice to shareholders.

Contingent Deferred Sales Charge. Class A and Class C shares are subject to a CDSC on certain redemptions. The CDSC generally is paid to the principal underwriter. Class A shares purchased at net asset value in amounts of $500,000 or more are subject to a 0.75% CDSC if redeemed within 12 months of purchase. Class C shares are subject to a 1.00% CDSC if redeemed within 12 months of purchase. CDSCs are based on the lower of the net asset value at the time of purchase or at the time of redemption. Shares acquired through the reinvestment of distributions are exempt from the CDSC. Redemptions are made first from shares that are not subject to a CDSC.

The sales commission payable to financial intermediaries in connection with sales of Class C shares is described under “Distribution and Service Fees” below.

CDSC Waivers. CDSCs are waived for certain redemptions pursuant to a Withdrawal Plan (see “Shareholder Account Features”) and in connection with certain redemptions from employer sponsored retirement plans or IRAs to satisfy required minimum distributions or to return excess contributions made to IRAs, if applicable. The CDSC is also waived following the death of a beneficial owner of shares (a death certificate and other applicable documents may be required). In addition, redemptions of Class C shares by certain employer sponsored retirement plans are not subject to a CDSC if the principal underwriter did not compensate such plans' financial intermediary at the time of sale as described under “Distribution and Service Fees.”

Calvert Responsible Municipal Income Fund25Prospectus dated May 1, 2024

Conversion Feature. Effective November 5, 2020 (the “Effective Date”), Class C shares of the Fund will convert automatically to Class A shares of the Fund during the month following the eight year anniversary of the purchase of such Class C shares. If a financial intermediary that maintains a Class C shareholder’s account has not tracked the holding period for Class C shares, Class C shares held as of the Effective Date will automatically convert to Class A shares eight years after the Effective Date. In addition, Class C shares held in an account with the Fund’s transfer agent for which no financial intermediary is specified and that are not subject to a CDSC will be converted to Class A shares of the Fund periodically.

In some circumstances, the Board may determine to cease to offer and subsequently close an existing class of Fund shares. In such circumstances, the Fund may automatically convert the shares for such class into another share class, subject to prior notice to shareholders of the impacted class. Any such conversion will occur at the respective net asset value of each class as of the conversion date without the imposition of any fee or other charges by the Fund.

Distribution and Service Fees. Class A and Class C shares have in effect plans under Rule 12b-1 that allow the Fund to pay distribution fees for the sale and distribution of shares and service fees for personal and/or shareholder account services (so-called “12b-1 fees”). Class C shares pay distribution fees to the principal underwriter of 0.75% of average daily net assets annually. Because these fees are paid from Fund assets on an ongoing basis, they will increase your cost over time and may cost you more than paying other types of sales charges. The principal underwriter generally compensates financial intermediaries on sales of Class C shares (except exchange transactions and reinvestments) in an amount equal to 1.00% of the purchase price of the shares. After the first year, such financial intermediaries also receive 0.75% of the value of outstanding Class C shares sold by such financial intermediaries in annual distribution fees. With respect to purchases of Class C shares by certain employer sponsored retirement plans, the principal underwriter does not compensate the financial intermediary at the time of sale. In such cases, the financial intermediary receives 0.75% of the value of outstanding Class C shares sold by such financial intermediary in annual distribution fees immediately after the sale. Class C shares also pay service fees to the principal underwriter equal to 0.25% of average daily net assets annually. Class A shares pay distribution and service fees equal to 0.25% of average daily net assets annually. After the sale of Class A shares, the principal underwriter receives the Class A distribution and service fees and generally the financial intermediary receives such fees immediately after the sale. After the sale of Class C shares, the principal underwriter generally receives the Class C service fees for one year, thereafter financial intermediaries generally receive such fees. With respect to purchases of Class C shares by certain employer sponsored retirement plans, the financial intermediary also receives the above described service fees from the principal underwriter immediately after the sale. Such amounts are generally paid to financial intermediaries by the principal underwriter based on the value of shares sold by such financial intermediaries for shareholder servicing performed by such intermediaries. Distribution and service fees are subject to the limitations contained in the sales charge rule of the Financial Industry Regulatory Authority, Inc.

More information about Fund sales charges is available free of charge on the Calvert website at www.calvert.com and in the SAI. Please consult the Calvert website for any updates to Fund sales charge information before making a purchase of Fund shares. Please consult your financial intermediary with respect to any sales charge variations listed on Appendix B.

Calvert Responsible Municipal Income Fund26Prospectus dated May 1, 2024

Redeeming Shares

You can redeem shares in any of the following ways:

By Mail	Send your request to the transfer agent (see back cover for address). The request must be signed exactly as your account is registered (for instance, a joint account must be signed by all registered owners to be accepted) and a Medallion signature guarantee may be required. Circumstances that may require a Medallion signature guarantee include, but are not limited to, requests to distribute redemption proceeds to a party other than the registered account owner(s); requests to mail redemption proceeds to an address other than the address of record; requests to distribute proceeds to a bank account not on file; requests to re-issue uncashed checks representing redemption proceeds; or transaction requests from an account beneficiary when an account owner is deceased. You can obtain a Medallion signature guarantee at banks, savings and loan institutions, credit unions, securities dealers, securities exchanges, clearing agencies and registered securities associations that participate in The Securities Transfer Agents Medallion Program, Inc. (STAMP, Inc.). Only Medallion signature guarantees issued in accordance with STAMP, Inc. will be accepted. You may be asked to provide additional documents if your shares are registered in the name of a corporation, partnership or fiduciary.
By Telephone	Certain shareholders can redeem by calling 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time). Proceeds of a telephone redemption are generally limited to $100,000 per account (which may include shares of one or more Calvert funds) and can be sent only to the account address or to a bank pursuant to prior instructions.
By Internet	Certain shareholders can redeem by logging on to the Calvert website at www.calvert.com. Proceeds of internet redemptions are generally limited to $100,000 per account (which may include shares of one or more Calvert funds) and can be sent only to the account address or to a bank pursuant to prior instructions.
For Additional Information	Please call 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time).
Through a Financial Intermediary	Your financial intermediary is responsible for transmitting the order promptly. A financial intermediary may charge a fee for this service.

A redemption may be requested by sending a Medallion signature guaranteed letter of instruction to the transfer agent (see back cover for address) or, for telephone redemptions as described above, by calling 1-800-368-2745. Certain redemption requests, including those involving shares held by certain corporations, trusts or certain other entities and shares that are subject to certain fiduciary arrangements, may require additional documentation and may be redeemed only by mail. The Fund's transfer agent or your financial intermediary must receive your redemption in proper form (meaning that it is complete and contains all necessary information) no later than the close of regular trading on the NYSE (normally 4:00 p.m. Eastern Time) for your redemption to be effected at that day’s net asset value. Redemption proceeds are reduced by the amount of any applicable CDSC and any federal income and state tax required to be withheld.

Redemption proceeds typically are paid to the redeeming shareholder in cash up to two business days after the redemption, but payment could take up to seven days, as permitted by the 1940 Act for the reasons discussed below. The actual number of days following receipt of a redemption request in which the Fund typically expects to pay redemption proceeds generally will depend on how you hold your shares with the Fund.

If your shares are held in a “street name” account with a financial intermediary (see “Shareholder Account Features – ‘Street Name’ Accounts”), your intermediary will elect through National Securities Clearing Corporation (“NSCC”) to settle redemptions either one business day or two business days after the redemption date and redemption proceeds normally will be wired to your financial intermediary on the settlement date pursuant to that election.

Calvert Responsible Municipal Income Fund27Prospectus dated May 1, 2024

If your shares are held directly with the Fund's transfer agent, redemptions normally will be settled in one business day after the redemption date and redemption proceeds will be sent by regular mail on such date. However, if you have given proper written authorization in advance, you may request that redemption proceeds be wired on the settlement date directly to your bank account in any bank in the United States. While not currently charged by the Fund, you may be required to pay a wire transfer fee by your bank. If you request expedited mail delivery of your redemption proceeds and the Fund is able to accommodate your request, charges may apply. You may redeem all or a portion of the shares from your account on any day the Fund is open for business, provided the amount requested is not on hold or held in escrow pursuant to a statement of intention. When you purchase by check or with ACH funds transfer, the purchase will be on hold for up to 10 days from the date of receipt. During the hold period, redemption proceeds will not be sent until the transfer agent is reasonably satisfied that the purchase payment has been collected.

The Fund typically expects to meet redemption requests by (i) distributing any cash holdings, (ii) selling portfolio investments and/or (iii) borrowing from a bank under a line of credit. In addition to the foregoing, the Fund also may distribute securities as payment (a so-called “redemption in-kind”), in which case the redeeming shareholder may pay fees and commissions to convert the securities to cash. Unless requested by a shareholder, the Fund generally expects to limit use of redemption in-kind to stressed market conditions, but is permitted to do so in other circumstances. A shareholder who wishes to receive redemption proceeds in-kind must notify the Fund on or before submitting the redemption request by calling 1-800-368-2745. Securities distributed in a redemption in-kind would be valued pursuant to the Fund’s valuation procedures and selected by the investment adviser. If a shareholder receives securities in a redemption in-kind, the shareholder could incur brokerage or other charges in converting the securities to cash and the value of such securities would be subject to price fluctuations until sold. There can be no assurance that the Fund will manage liquidity successfully in all market environments. As a result, the Fund may not be able to pay redemption proceeds in a timely fashion because of unusual market conditions, an unusually high volume of redemption requests or other factors. Additional information about redemptions in-kind, including the procedures for submitting such redemption requests, is contained in the Fund’s SAI.

If your account value falls below $750, you may be asked either to add to your account or redeem it within 60 days. If you take no action, your account will be redeemed at net asset value and the proceeds sent to you.

Shareholder Account Features

Distributions. You may have your Fund distributions paid in one of the following ways:

• Full Reinvest Option	Distributions are reinvested in additional shares. This option will be assigned if you do not specify an option.
• Partial Reinvest Option	Dividends and short-term capital gains are paid in cash* and long-term capital gains are reinvested in additional shares.
• Cash Option	Distributions are paid in cash.*
• Exchange Option	Distributions are reinvested in additional shares of any class of another Calvert fund chosen by you, subject to the terms of that fund’s prospectus. Before selecting this option, you must obtain a prospectus of the other fund and consider its objectives, risks, and charges and expenses carefully.

*If any distribution check remains uncashed for six months, CRM reserves the right to invest the amount represented by the check in Fund shares at the then-current net asset value of a Fund and all future distributions will be reinvested. For accounts held directly with a Fund’s transfer agent for which the shareholder has elected to receive distributions via check, any distribution (dividend or capital gain) under $10.00 is automatically reinvested in additional shares regardless of your elected distribution option.

Information about the Fund. From time to time, you may receive the following:

·Semiannual and annual reports containing a list of portfolio holdings as of the end of the second and fourth fiscal quarters, respectively, performance information and financial statements.

·Periodic account statements, showing recent activity and total share balance.

·Tax information needed to prepare your income tax returns.

·Proxy materials, in the event a shareholder vote is required.

·Special notices about significant events affecting your Fund.

Most fund information (including semiannual and annual reports, prospectuses and proxy statements) as well as your periodic account statements can be delivered electronically. For more information please go to www.calvert.com.

Calvert Responsible Municipal Income Fund28Prospectus dated May 1, 2024

You may be contacted via mail, telephone or by electronic means by officers of the Fund, by personnel of the investment adviser or administrator, by the Fund’s transfer agent, by broker-dealer firms, or by a professional solicitation organization in connection with a solicitation of proxies for a meeting of Fund shareholders.

The Calvert funds have established policies and procedures with respect to the disclosure of portfolio holdings and other information concerning Fund characteristics. A description of these policies and procedures is provided below and additionally in the SAI. Such policies and procedures regarding disclosure of portfolio holdings are designed to prevent the misuse of material, non-public information about the funds.

The Fund will file information regarding its portfolio holdings with the SEC on its Form N-PORT. The Fund’s annual and semiannual reports (as filed on Form N-CSR) and certain information filed on Form N-PORT may be viewed on the SEC’s website (www.sec.gov). The most recent fiscal quarter-end holdings may also be viewed on the Calvert website (www.calvert.com). Portfolio holdings information that is filed with the SEC is posted on the Calvert website approximately 60 days after the end of the quarter to which it relates. Portfolio holdings information as of each month end is posted to the website approximately one month after such month end. The Fund also posts information about certain portfolio characteristics (such as top ten holdings and asset allocation) at least quarterly on the Calvert website approximately ten business days after the period and the Fund may also post performance attribution as of a month end or more frequently if deemed appropriate.

Withdrawal Plan. You may redeem shares on a regular periodic basis by establishing a systematic withdrawal plan. Withdrawals will not be subject to any applicable CDSC if they are, in the aggregate, less than or equal to 12% annually of the greater of either the initial account balance or the current account balance. Because purchases of Class A shares are generally subject to an initial sales charge, Class A shareholders should not make withdrawals from their accounts while also making purchases.

Exchange Privilege. Each class of Fund shares may be exchanged for shares of the same Class of another Calvert fund. Exchanges are made at net asset value. If your shares are subject to a CDSC, the CDSC will continue to apply to your new shares at the same CDSC rate. For purposes of the CDSC, your shares will continue to age from the date of your original purchase of Fund shares. Except as described below, any class of shares of a fund may be exchanged for any other class of shares of that fund, provided that the shares being exchanged are no longer subject to a CDSC and the conditions for investing in the other class of shares described in the applicable prospectus are satisfied. Class C shares are not permitted to be exchanged to Class A shares unless the CDSC has expired and the exchange is made to facilitate the shareholder's participation in a fee-based advisory program. See also Appendix B to this Prospectus.

Before exchanging, you should read the prospectus of the new fund carefully. Exchanges are subject to the terms applicable to purchases of the new fund’s shares as set forth in its prospectus. If you wish to exchange shares, write to the transfer agent (see back cover for address), log on to your account at www.calvert.com or call 1-800-368-2745. Periodic automatic exchanges are also available. The exchange privilege may be changed or discontinued at any time. You will receive at least 60 days’ notice of any material change to the privilege. This privilege may not be used for “market timing” and may be terminated for market timing accounts or for any other reason. For additional information, see “Restrictions on Excessive Trading and Market Timing” under “Purchasing Shares.” Ordinarily exchanges between different funds are taxable transactions for federal tax purposes, while permitted exchanges of one class for shares of another class of the same fund are not. Shareholders should consult their tax advisors regarding the applicability of federal, state, local and other taxes to transactions in Fund shares.

Reinvestment Privilege. If you redeem shares, you may reinvest at net asset value all or any portion of the redemption proceeds in the same account and in the same class of shares of the Fund you redeemed from or another Fund, provided that the reinvestment occurs within 90 days of the redemption, the privilege has not been used more than once in the prior 12 months, the redeemed shares were subject to a front-end sales charge or CDSC and that you are otherwise eligible to invest in that class. Under these circumstances your account will be credited with any CDSC paid in connection with the redemption. Any CDSC period applicable to the shares you acquire upon reinvestment will run from the date of your original share purchase. For requests for reinvestment sent to the Fund's transfer agent, the request must be in writing. At the time of a reinvestment, you or your financial intermediary must notify the Fund or the transfer agent that you are reinvesting redemption proceeds in accordance with this privilege. If you reinvest, your purchase will be at the next determined net asset value following receipt of your request.

Telephone and Electronic Transactions. You can redeem or exchange shares by telephone as described in this Prospectus. In addition, certain transactions may be conducted through the Calvert website. The transfer agent and the principal underwriter have procedures in place to authenticate telephone and electronic instructions (such as using security codes or verifying personal account information). As long as the transfer agent and principal underwriter follow reasonable procedures, they will not be responsible for unauthorized telephone or electronic transactions and you bear the risk of possible loss resulting from these transactions. You may decline the telephone redemption option on the

Calvert Responsible Municipal Income Fund29Prospectus dated May 1, 2024

account application. Telephone instructions are recorded. You should verify the accuracy of your confirmation statements immediately upon receipt and notify Calvert Shareholder Services of any inaccuracies.

“Street Name” Accounts. If your shares are held in a “street name” account at a financial intermediary, that intermediary (and not the Fund or its transfer agent) will perform all recordkeeping, transaction processing and distribution payments. Because the Fund does not maintain an account for you, you should contact your financial intermediary to make transactions in shares, make changes in your account, or obtain account information. You will not be able to utilize a number of shareholder features, such as telephone or internet transactions, directly with the Fund and certain features may be subject to different requirements. If you transfer shares in a “street name” account to an account with another financial intermediary or to an account directly with the Fund, you should obtain historical information about your shares prior to the transfer. If you fail to provide your full account history to your new financial intermediary following a transfer, you may be ineligible for certain features of the Fund.

Procedures for Opening New Accounts. To help the government fight the funding of terrorism and money laundering activities, federal law requires financial institutions to obtain, verify and record information that identifies each new customer who opens an account with the Fund and to determine whether such person’s name appears on government lists of known or suspected terrorists or terrorist organizations. When you open an account, the transfer agent or your financial intermediary will ask you for your name, address, date of birth (for individuals), residential or business street address (although post office boxes are still permitted for mailing) and social security number, taxpayer identification number, or other government-issued identifying number. You also may be asked to produce a copy of your driver’s license, passport or other identifying documents in order to verify your identity. In addition, it may be necessary to verify your identity by cross-referencing your identification information with a consumer report or other electronic databases. Other information or documents may be required to open accounts for corporations and other entities. Federal law prohibits the Fund and other financial institutions from opening a new account unless they receive the minimum identifying information described above. If a person fails to provide the information requested, any application by that person to open a new account will be rejected. Moreover, if the transfer agent or the financial intermediary is unable to verify the identity of a person based on information provided by that person, it may take additional steps including, but not limited to, requesting additional information or documents from the person, closing the person’s account or reporting the matter to the appropriate federal authorities. If your account is closed for this reason, your shares may be automatically redeemed at the net asset value next determined. If the Fund’s net asset value has decreased since your purchase, you will lose money as a result of this redemption. The Fund has also designated an anti-money laundering compliance officer.

Account Questions. If you have any questions about your account or the services available, please call Calvert Shareholder Services at 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time), or write to the transfer agent (see back cover for address).

Potential Conflicts of Interest

As a diversified global financial services firm, Morgan Stanley, the parent company of the investment adviser, engages in a broad spectrum of activities, including financial advisory services, investment management activities, lending, commercial banking, sponsoring and managing private investment funds, engaging in broker-dealer transactions and principal securities, commodities and foreign exchange transactions, research publication and other activities. In the ordinary course of its business, Morgan Stanley is a full-service investment banking and financial services firm and therefore engages in activities where Morgan Stanley’s interests or the interests of its clients may conflict with the interests of a Fund or Portfolio, as applicable (collectively, for purposes of this section, “Fund” or “Funds”). Morgan Stanley advises clients and sponsors, manages or advises other investment funds and investment programs, accounts and businesses (collectively, together with any new or successor Morgan Stanley funds, programs, accounts or businesses, (other than funds, programs, accounts or businesses sponsored, managed, or advised by former direct or indirect subsidiaries of Eaton Vance Corp. (“Eaton Vance Investment Accounts”)), the “MS Investment Accounts,” and, together with the Eaton Vance Investment Accounts, the ‘‘Affiliated Investment Accounts’’) with a wide variety of investment objectives that in some instances may overlap or conflict with a Fund’s investment objectives and present conflicts of interest. In addition, Morgan Stanley or the investment adviser may also from time to time create new or successor Affiliated Investment Accounts that may compete with a Fund and present similar conflicts of interest. The discussion below enumerates certain actual, apparent and potential conflicts of interest. There is no assurance that conflicts of interest will be resolved in favor of Fund shareholders and, in fact, they may not be. Conflicts of interest not described below may also exist.

The discussions below with respect to actual, apparent and potential conflicts of interest also may be applicable to or arise from the MS Investment Accounts whether or not specifically identified. For more information about conflicts of interest, see the section entitled “Potential Conflicts of Interest” in the SAI.

Calvert Responsible Municipal Income Fund30Prospectus dated May 1, 2024

Material Non-Public Information. It is expected that confidential or material non-public information regarding an investment or potential investment opportunity may become available to the investment adviser. If such information becomes available, the investment adviser may be precluded (including by applicable law or internal policies or procedures) from pursuing an investment or disposition opportunity with respect to such investment or investment opportunity. Morgan Stanley has established certain information barriers and other policies to address the sharing of information between different businesses within Morgan Stanley. In limited circumstances, however, including for purposes of managing business and reputational risk, and subject to policies and procedures and any applicable regulations, Morgan Stanley personnel, including personnel of the investment adviser, on one side of an information barrier may have access to information and personnel on the other side of the information barrier through “wall crossings.” The investment adviser faces conflicts of interest in determining whether to engage in such wall crossings. Information obtained in connection with such wall crossings may limit or restrict the ability of the investment adviser to engage in or otherwise effect transactions on behalf of the Fund(s) (including purchasing or selling securities that the investment adviser may otherwise have purchased or sold for a Fund in the absence of a wall crossing).

Investments by Morgan Stanley and its Affiliated Investment Accounts. In serving in multiple capacities to Affiliated Investment Accounts, Morgan Stanley, including the investment adviser and its investment teams, may have obligations to other clients or investors in Affiliated Investment Accounts, the fulfillment of which may not be in the best interests of a Fund or its shareholders. A Fund’s investment objectives may overlap with the investment objectives of certain Affiliated Investment Accounts. As a result, the members of an investment team may face conflicts in the allocation of investment opportunities among a Fund and other investment funds, programs, accounts and businesses advised by or affiliated with the investment adviser. Certain Affiliated Investment Accounts may provide for higher management or incentive fees or greater expense reimbursements or overhead allocations, all of which may contribute to this conflict of interest and create an incentive for the investment adviser to favor such other accounts. To seek to reduce potential conflicts of interest and to attempt to allocate such investment opportunities in a fair and equitable manner, the investment adviser has implemented allocation policies and procedures. These policies and procedures are intended to give all clients of the investment adviser, including the Fund(s), fair access to investment opportunities consistent with the requirements of organizational documents, investment strategies, applicable laws and regulations, and the fiduciary duties of the investment adviser.

Investments by Separate Investment Departments. The entities and individuals that provide investment-related services for the Fund and certain other Eaton Vance Investment Accounts (the “Eaton Vance Investment Department”) may be different from the entities and individuals that provide investment-related services to MS Investment Accounts (the “MS Investment Department” and, together with the Eaton Vance Investment Department, the “Investment Departments”). Although Morgan Stanley has implemented information barriers between the Investment Departments in accordance with internal policies and procedures, each Investment Department may engage in discussions and share information and resources with the other Investment Department on certain investment-related matters. A MS Investment Account could trade in advance of a Fund (and vice versa), might complete trades more quickly and efficiently than a Fund, and/or achieve different execution than a Fund on the same or similar investments made contemporaneously, even when the Investment Departments shared research and viewpoints that led to that investment decision. Any sharing of information or resources between the Investment Department servicing the Fund and the MS Investment Department may result, from time to time, in a Fund simultaneously or contemporaneously seeking to engage in the same or similar transactions as an account serviced by the other Investment Department and for which there are limited buyers or sellers on specific securities, which could result in less favorable execution for the Fund than such account.

Payments to Broker-Dealers and Other Financial Intermediaries. The investment adviser and/or Eaton Vance Distributors, Inc. (“EVD”) may pay compensation, out of their own funds and not as an expense of a Fund, to certain financial intermediaries (which may include affiliates of the investment adviser and EVD), including recordkeepers and administrators of various deferred compensation plans, in connection with the sale, distribution, marketing and retention of shares of the Fund and/or shareholder servicing. The prospect of receiving, or the receipt of, additional compensation, as described above, by financial intermediaries may provide such financial intermediaries and their financial advisors and other salespersons with an incentive to favor sales of shares of a Fund over other investment options with respect to which these financial intermediaries do not receive additional compensation (or receive lower levels of additional compensation). These payment arrangements, however, will not change the price that an investor pays for shares of a Fund or the amount that the Fund receives to invest on behalf of an investor. Investors may wish to take such payment arrangements into account when considering and evaluating any recommendations relating to Fund shares and should review carefully any disclosures provided by financial intermediaries as to their compensation. In addition, in certain circumstances, the investment adviser may restrict, limit or reduce the amount of a Fund’s investment, or restrict the type of governance or voting rights it acquires or exercises, where the Fund (potentially together with Morgan Stanley) exceeds a certain ownership interest, or possesses certain degrees of voting or control or has other interests.

Calvert Responsible Municipal Income Fund31Prospectus dated May 1, 2024

Morgan Stanley Trading and Principal Investing Activities. Notwithstanding anything to the contrary herein, Morgan Stanley will generally conduct its sales and trading businesses, publish research and analysis, and render investment advice without regard for a Fund’s holdings, although these activities could have an adverse impact on the value of one or more of the Fund’s investments, or could cause Morgan Stanley to have an interest in one or more portfolio investments that is different from, and potentially adverse to, that of a Fund.

Morgan Stanley’s Investment Banking and Other Commercial Activities. Morgan Stanley advises clients on a variety of mergers, acquisitions, restructuring, bankruptcy and financing transactions. Morgan Stanley may act as an advisor to clients, including other investment funds that may compete with a Fund and with respect to investments that a Fund may hold. Morgan Stanley may give advice and take action with respect to any of its clients or proprietary accounts that may differ from the advice given, or may involve an action of a different timing or nature than the action taken, by a Fund. Morgan Stanley may give advice and provide recommendations to persons competing with a Fund and/or any of a Fund’s investments that are contrary to the Fund’s best interests and/or the best interests of any of its investments. Morgan Stanley’s activities on behalf of its clients (such as engagements as an underwriter or placement agent) may restrict or otherwise limit investment opportunities that may otherwise be available to a Fund.

Morgan Stanley may be engaged to act as a financial advisor to a company in connection with the sale of such company, or subsidiaries or divisions thereof, may represent potential buyers of businesses through its mergers and acquisition activities and may provide lending and other related financing services in connection with such transactions. Morgan Stanley’s compensation for such activities is usually based upon realized consideration and is usually contingent, in substantial part, upon the closing of the transaction. Under these circumstances, a Fund may be precluded from participating in a transaction with or relating to the company being sold or participating in any financing activity related to the merger or acquisition.

General Process for Potential Conflicts. All of the transactions described above involve the potential for conflicts of interest between the investment adviser, related persons of the investment adviser and/or their clients. The Investment Advisers Act of 1940, as amended (the “Advisers Act”), the 1940 Act and ERISA impose certain requirements designed to decrease the possibility of conflicts of interest between an investment adviser and its clients. In some cases, transactions may be permitted subject to fulfillment of certain conditions. Certain other transactions may be prohibited. In addition, the investment adviser has instituted policies and procedures designed to prevent conflicts of interest from arising and, when they do arise, to ensure that it effects transactions for clients in a manner that is consistent with its fiduciary duty to its clients and in accordance with applicable law. The investment adviser seeks to ensure that potential or actual conflicts of interest are appropriately resolved taking into consideration the overriding best interests of the client.

Additional Tax Information

The Fund declares distributions daily and ordinarily pays distributions monthly. Different classes may distribute different amounts. Your account will be credited with distributions beginning on the business day after the day when the funds used to purchase your Fund shares are collected by the transfer agent. For tax purposes, provided certain requirements are met, the entire monthly distribution of the Fund’s daily distributions ordinarily will constitute exempt interest-dividend income to you that is exempt from U.S. federal income tax. The exemption of “exempt-interest dividend” income from U.S. federal income taxation does not necessarily result in similar exemptions of such income under state or local tax laws. The Fund intends to distribute net realized gains (if any) annually. It may also be necessary, in order to qualify for favorable tax treatment and to avoid any Fund-level tax, for the Fund to make a special income and/or capital gains distribution at the end of the calendar year.

The net investment income of certain U.S. individuals, estates and trusts is subject to a 3.8% Medicare contribution tax. For individuals, the tax is on the lesser of “net investment income” and the excess of modified adjusted gross income over certain threshold amounts. Net investment income includes, among other things, interest, dividends (other than exempt-interest dividends) and capital gains derived from passive activities and trading in securities or commodities. Net investment income is reduced by deductions “properly allocable” to this income.

Any recognized gain or income attributable to market discount on long-term tax-exempt municipal obligations (i.e., obligations with a term of more than one year) generally is taxable as ordinary income to the extent the gain or income does not exceed the “accrued market discount” on such obligation. A long-term debt obligation is generally treated as acquired at a market discount if it is purchased after its original issue at a price less than (i) the stated principal amount payable at maturity, in the case of an obligation that does not have original issue discount or (ii) in the case of an obligation that does have original issue discount, the sum of the issue price and any original issue discount that accrued before the Fund purchased the obligation, in both cases, subject to a de minimis exclusion.

Calvert Responsible Municipal Income Fund32Prospectus dated May 1, 2024

The Fund may invest a portion of its assets in securities that generate income that is not exempt from U.S. federal income tax. The rate of taxes on distributions of capital gains is determined by how long the Fund owned (or is treated as having owned) the investments that generated them, rather than how long a shareholder has owned his or her shares in the Fund. Distributions of taxable income and net short-term capital gains will generally be taxable as ordinary income. Distributions of net gains from investments held for more than one year are generally taxable as long-term capital gains. Distributions of interest on certain municipal obligations are a tax preference item under the Alternative Minimum Tax (the “AMT”) provisions of the Code applicable to individuals. Therefore, an investment in the Fund may result in liability for the U.S. federal AMT for shareholders subject to such tax. As long as a return of capital does not exceed a shareholder's cost basis in its shares, it generally will not be taxable to the shareholder but will reduce the cost basis of the shareholder's shares and result in a higher reported capital gain or a lower reported capital loss on a subsequent taxable disposition of such shares. The Fund’s distributions will be treated as described above for U.S. federal income tax purposes regardless of whether they are paid in cash or reinvested in additional shares. A redemption of Fund shares, including an exchange for shares of another fund, is generally a taxable transaction.

The Fund may be required to withhold, for U.S. federal income tax purposes, a portion of the dividends, distributions and redemption proceeds payable to shareholders who fail to provide the Fund with their correct taxpayer identification number or make required certifications, or who have been notified by the Internal Revenue Service (the “IRS”) that they are subject to backup withholding. Certain shareholders are exempt from backup withholding. Backup withholding is not an additional tax and any amount withheld may be credited against a shareholder’s U.S. federal income tax liability.

Certain foreign entities may be subject to a 30% withholding tax on ordinary dividend income paid under the Foreign Account Tax Compliance Act (“FATCA”). To avoid withholding, foreign financial institutions subject to FATCA must agree to disclose to the relevant revenue authorities certain information regarding their direct and indirect U.S. owners and other foreign entities must certify certain information regarding their direct and indirect U.S. owners to the Fund. In addition, the IRS and the Department of the Treasury have issued proposed regulations providing that these withholding rules will not be applicable to the gross proceeds of share redemptions or capital gain dividends the Fund pays. For more detailed information regarding FATCA withholding and compliance, please refer to the SAI.

Shareholders, particularly corporations, recipients of social security or railroad retirement benefits and those subject to the AMT, should consult with their tax advisors concerning the applicability of U.S. federal, state, local and other taxes, including non-U.S. taxes, to an investment.

Calvert Responsible Municipal Income Fund33Prospectus dated May 1, 2024

Financial Highlights

The financial highlights are intended to help you understand the Fund’s financial performance for the period(s) indicated. Certain information in the table reflects the financial results for a single Fund share. The total returns in the table represent the rate an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all distributions at net asset value). This information has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, except that information for the year ended December 31, 2020 and prior was audited by another independent registered public accounting firm. The report of Deloitte & Touche LLP and the Fund’s financial statements are incorporated herein by reference and included in the Fund’s annual report, which is available upon request.

	Year Ended December 31,
	2023			2022
	Class A	Class C	Class I	Class A	Class C	Class I
Net asset value - Beginning of year	$15.06	$15.06	$15.10	$16.69	$16.69	$16.73
Income (Loss) From Operations
Net investment income(1)	$0.41	$0.30	$0.45	$0.26	$0.14	$0.30
Net realized and unrealized gain (loss)	0.40	0.40	0.40	(1.63)	(1.62)	(1.63)
Total income (loss) from operations	$0.81	$0.70	$0.85	$(1.37)	$(1.48)	$(1.33)
Less Distributions
From net investment income	$(0.41)	$(0.30)	$(0.45)	$(0.26)	$(0.15)	$(0.30)
Total distributions	$(0.41)	$(0.30)	$(0.45)	$(0.26)	$(0.15)	$(0.30)
Net asset value – End of year	$15.46	$15.46	$15.50	$15.06	$15.06	$15.10
Total Return(2)	5.50%	4.71%	5.75%	(8.20)%	(8.89)%	(7.94)%
Ratios/Supplemental Data
Net assets, end of year (000’s omitted)	$105,114	$1,179	$337,131	$109,974	$1,462	$314,760
Ratios (as a percentage of average daily net assets):(3)
Total expenses	0.89%	1.64%	0.64%	0.88%	1.63%	0.63%
Net expenses(4)	0.75%	1.50%	0.50%	0.75%	1.50%	0.50%
Net investment income	2.73%	1.97%	2.97%	1.69%	0.89%	1.97%
Portfolio Turnover	54%	54%	54%	88%	88%	88%

(See related footnotes.)

Calvert Responsible Municipal Income Fund34Prospectus dated May 1, 2024

Financial Highlights (continued)

	Year Ended December 31,
	2021			2020			2019
	Class A	Class C	Class I	Class A	Class C	Class I	Class A	Class C	Class I
Net asset value – Beginning of year	$16.83	$16.83	$16.88	$16.36	$16.36	$16.40	$15.61	$15.61	$15.65
Income (Loss) From Operations
Net investment income(1)	$0.17	$0.04	$0.21	$0.24	$0.11	$0.26	$0.35	$0.22	$0.39
Net realized and unrealized gain (loss)	(0.14)	(0.13)	(0.15)	0.47	0.48	0.50	0.75	0.76	0.76
Total income (loss) from operations	$0.03	$(0.09)	$0.06	$0.71	$0.59	$0.76	$1.10	$0.98	$1.15
Less Distributions
From net investment income	$(0.17)	$(0.05)	$(0.21)	$(0.24)	$(0.12)	$(0.28)	$(0.35)	$(0.23)	$(0.40)
Total distributions	$(0.17)	$(0.05)	$(0.21)	$(0.24)	$(0.12)	$(0.28)	$(0.35)	$(0.23)	$(0.40)
Net asset value – End of year	$16.69	$16.69	$16.73	$16.83	$16.83	$16.88	$16.36	$16.36	$16.40
Total Return(2)	0.19%	(0.56)%	0.38%	4.38%	3.60%	4.69%	7.10%	6.29%	7.38%
Ratios/Supplemental Data
Net assets, end of year (000’s omitted)	$128,437	$2,258	$304,069	$128,384	$2,249	$242,113	$117,964	$1,510	$66,218
Ratios (as a percentage of average daily net assets):(3)
Total expenses	0.87%	1.62%	0.62%	0.88%	1.62%	0.63%	0.96%	1.71%	0.71%
Net expenses	0.75%	1.50%	0.50%	0.75%	1.50%	0.50%	0.77%	1.51%	0.49%
Net investment income	1.02%	0.27%	1.27%	1.45%	0.67%	1.59%	2.15%	1.37%	2.39%
Portfolio Turnover	18%	18%	18%	14%	14%	14%	18%	18%	18%

(1)Computed using average shares outstanding.

(2)Returns are historical and are calculated by determining the percentage change in net asset value with all distributions reinvested and do not reflect the effect of sales charges, if any.

(3)Total expenses do not reflect amounts reimbursed and/or waived by the adviser and certain of its affiliates, if applicable. Net expenses are net of all reductions and represent the net expenses paid by the Fund.

(4)Includes a reduction by the investment adviser of a portion of its advisory fee due to the Fund’s investment in the Morgan Stanley Institutional Liquidity Funds – Government Portfolio (equal to less than 0.005% of average daily net assets for the years ended December 31, 2023 and 2022).

Calvert Responsible Municipal Income Fund35Prospectus dated May 1, 2024

Appendix A

The Calvert Principles for Responsible Investment

We believe that most corporations deliver benefits to society, through their products and services, creation of jobs, payment of taxes and the sum of their behaviors. As a responsible investor, Calvert Research and Management seeks to invest in companies and other issuers that provide positive leadership in the areas of their operations and overall activities that are material to improving long-term shareholder value and societal outcomes.

Calvert seeks to invest in issuers that balance the needs of financial and nonfinancial stakeholders and demonstrate a commitment to the global commons, as well as to the rights of individuals and communities.

The Calvert Principles for Responsible Investment (Calvert Principles) provide a framework for Calvert’s evaluation of investments and guide Calvert’s stewardship on behalf of clients through active engagement with issuers. The Calvert Principles seek to identify companies and other issuers that operate in a manner that is consistent with or promote:

Environmental Sustainability and Resource Efficiency

·Reduce the negative impact of operations and practices on the environment

·Manage water scarcity and ensure efficient and equitable access to clean sources

·Mitigate impact on all types of natural capital

·Diminish climate-related risks and reduce carbon emissions

·Drive sustainability innovation and resource efficiency through business operations or other activities, products and services

Equitable Societies and Respect for Human Rights

·Respect consumers by marketing products and services in a fair and ethical manner, maintaining integrity in customer relations and ensuring the security of sensitive consumer data

·Respect human rights, respect culture and tradition in local communities and economies, and respect Indigenous Peoples’ Rights

·Promote diversity and gender equity across workplaces, marketplaces and communities

·Demonstrate a commitment to employees by promoting development, communication, appropriate economic opportunity and decent workplace standards

·Respect the health and well-being of consumers and other users of products and services by promoting product safety

Accountable Governance and Transparency

·Provide responsible stewardship of capital in the best interests of shareholders and debtholders

·Exhibit accountable governance and develop effective boards or other governing bodies that reflect expertise and diversity of perspective and provide oversight of sustainability risk and opportunity

·Include environmental and social risks, impacts and performance in material financial disclosures to inform shareholders and debtholders, benefit stakeholders and contribute to strategy

·Lift ethical standards in all operations, including in dealings with customers, regulators and business partners

·Demonstrate transparency and accountability in addressing adverse events and controversies while minimizing risks and building trust

Through the application of the Calvert Principles, Calvert could have no or limited exposure to issuers that:

·Demonstrate poor management of environmental risks or contribute significantly to local or global environmental problems.

·Demonstrate a pattern of employing forced, compulsory or child labor.

·Exhibit a pattern and practice directly or through the company’s supply chain of human rights violations or are complicit in human rights violations committed by governments or security forces, including those that are under U.S. or international sanction for human rights abuses.

·Exhibit a pattern and practice of violating the rights and protections of Indigenous Peoples.

·Demonstrate poor governance or engage in harmful or unethical practices.

·Manufacture tobacco products.

·Have significant and direct involvement in the manufacture of alcoholic beverages without taking significant steps to reduce the harmful impact of these products.

Calvert Responsible Municipal Income Fund36Prospectus dated May 1, 2024

·Have significant and direct involvement in gambling or gaming operations without taking significant steps to reduce the harmful impact of these businesses.

·Have significant and direct involvement in the manufacture of civilian handguns and/or automatic weapons marketed to civilians.

·Have significant and direct involvement in the manufacture of military weapons that violate international humanitarian law, including cluster bombs, landmines, biochemical weapons, nuclear weapons, blinding laser weapons, or incendiary weapons.

·Use animals in product testing without countervailing social benefits such as the development of medical treatments to ease human suffering and disease.

Calvert Responsible Municipal Income Fund37Prospectus dated May 1, 2024

Appendix B

Financial Intermediary Sales Charge Variations

As noted under “Purchasing Shares,” a financial intermediary may offer Fund shares subject to variations in or elimination of the Fund sales charges (“variations”), provided such variations are described in this Prospectus. Set forth below are the variations in sales charges applicable to shares purchased through the noted financial intermediary. All variations described below are applied by, and the responsibility of, the identified financial intermediary. Variations may apply to purchases, sales, exchanges and reinvestments of Fund shares and a shareholder transacting in Fund shares through the intermediary identified below should read the terms and conditions of the variations carefully. A variation that is specific to a particular financial intermediary is not applicable to shares held directly with the Fund or through another intermediary.

Fund Purchases through Merrill Lynch

Purchases or sales of front-end (i.e. Class A) or level-load (i.e., Class C) mutual fund shares through a Merrill platform or account will be eligible only for the following sales load waivers (front-end, contingent deferred, or back-end waivers) and discounts, which differ from those disclosed elsewhere in this Fund’s prospectus. Purchasers will have to buy mutual fund shares directly from the mutual fund company or through another intermediary to be eligible for waivers or discounts not listed below.

It is the client’s responsibility to notify Merrill at the time of purchase or sale of any relationship or other facts that qualify the transaction for a waiver or discount. A Merrill representative may ask for reasonable documentation of such facts and Merrill may condition the granting of a waiver or discount on the timely receipt of such documentation.

Additional information on waivers and discounts is available in the Merrill Sales Load Waiver and Discounts Supplement (the “Merrill SLWD Supplement”) and in the Mutual Fund Investing at Merrill pamphlet at ml.com/funds. Clients are encouraged to review these documents and speak with their financial advisor to determine whether a transaction is eligible for a waiver or discount.

Front-end Load Waivers Available at Merrill

·Shares of mutual funds available for purchase by employer-sponsored retirement, deferred compensation and employee benefit plans (including health savings accounts) and trusts used to fund those plans provided the shares are not held in a commission-based brokerage account and shares are held for the benefit of the plan. For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans

·Shares purchased through a Merrill investment advisory program

·Brokerage class shares exchanged from advisory class shares due to the holdings moving from a Merrill investment advisory program to a Merrill brokerage account

·Shares purchased through the Merrill Edge Self-Directed platform

·Shares purchased through the systematic reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same mutual fund in the same account

·Shares exchanged from level-load shares to front-end load shares of the same mutual fund in accordance with the description in the Merrill SLWD Supplement

·Shares purchased by eligible employees of Merrill or its affiliates and their family members who purchase shares in accounts within the employee’s Merrill Household (as defined in the Merrill SLWD Supplement)

·Shares purchased by eligible persons associated with the fund as defined in this prospectus (e.g. the fund’s officers or trustees)

·Shares purchased from the proceeds of a mutual fund redemption in front-end load shares provided (1) the repurchase is in a mutual fund within the same fund family; (2) the repurchase occurs within 90 calendar days from the redemption trade date; and (3) the redemption and purchase occur in the same account (known as Rights of Reinstatement). Automated transactions (i.e. systematic purchases and withdrawals) and purchases made after shares are automatically sold to pay Merrill’s account maintenance fees are not eligible for Rights of Reinstatement

CDSC Waivers on Front-end, Back-end and Level Load Shares Available at Merrill

·Shares sold due to the client’s death or disability (as defined by Internal Revenue Code Section 22e(3))

·Shares sold pursuant to a systematic withdrawal program subject to Merrill’s maximum systematic withdrawal limits as described in the Merrill SLWD Supplement

·Shares sold due to return of excess contributions from an IRA account

Calvert Responsible Municipal Income Fund38Prospectus dated May 1, 2024

·Shares sold as part of a required minimum distribution for IRA and retirement accounts due to the investor reaching the qualified age based on applicable IRS regulation

·Front-end or level-load shares held in commission-based, non-taxable retirement brokerage accounts (e.g. traditional, Roth, rollover, SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans) that are transferred to fee-based accounts or platforms and exchanged for a lower cost share class of the same mutual fund

Front-end Load Discounts Available at Merrill: Breakpoints, Rights of Accumulation & Letters of Intent

·Breakpoint discounts, as described in this prospectus, where the sales load is at or below the maximum sales load that Merrill permits to be assessed to a front-end load purchase, as described in the Merrill SLWD Supplement

·Rights of Accumulation (ROA), as described in the Merrill SLWD Supplement, which entitle clients to breakpoint discounts based on the aggregated holdings of mutual fund family assets held in accounts in their Merrill Household

·Letters of Intent (LOI), which allow for breakpoint discounts on eligible new purchases based on anticipated future eligible purchases within a fund family at Merrill, in accounts within your Merrill Household, as further described in the Merrill SLWD Supplement

Calvert Responsible Municipal Income Fund39Prospectus dated May 1, 2024

Fund Purchases through Ameriprise Financial (Class A Sales Charge Waivers)

The following information applies to Class A share purchases if you have an account with or otherwise purchase Fund shares through Ameriprise Financial:

Effective January 15, 2021, shareholders purchasing Fund shares through an Ameriprise Financial retail brokerage account are eligible for the following front-end sales charge waivers, which may differ from those disclosed elsewhere in this Prospectus or in the SAI.

·Employer-sponsored retirement plans (e.g., 401(k) plans 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans). For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs or SAR-SEPs.

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same Fund (but not any other fund within the same fund family).

·Shares exchanged from Class C shares of the same fund in the month of or following the 7-year anniversary of the purchase date. To the extent that this Prospectus elsewhere provides for a waiver with respect to exchanges of Class C shares or conversion of Class C shares following a shorter holding period, that waiver will apply.

·Employees and registered representatives of Ameriprise Financial or its affiliates and their immediate family members.

·Shares purchased by or through qualified accounts (including IRAs, Coverdell Education Savings Accounts, 401(k)s, 403(b) TSCAs subject to ERISA and defined benefit plans) that are held by a covered family member, defined as an Ameriprise financial advisor and/or the advisor’s spouse, advisor’s lineal ascendant (mother, father, grandmother, grandfather, great grandmother, great grandfather), advisor’s lineal descendant (son, step-son, daughter, step-daughter, grandson, granddaughter, great grandson, great granddaughter) or any spouse of a covered family member who is a lineal descendant.

·Shares purchased from the proceeds of redemptions within the same fund family, provided (1) the repurchase occurs within 90 days following the redemption, (2) the redemption and purchase occur in the same account, and (3) redeemed shares were subject to a front-end or deferred sales load (i.e. Rights of Reinstatement).

Calvert Responsible Municipal Income Fund40Prospectus dated May 1, 2024

Fund Purchases through Morgan Stanley Wealth Management

Effective July 1, 2018, shareholders purchasing Fund shares through a Morgan Stanley Wealth Management transactional brokerage account will be eligible only for the following front-end sales charge waivers with respect to Class A shares, which may differ from and may be more limited than those disclosed elsewhere in this Prospectus or SAI.

Front-end Sales Charge Waivers on Class A Shares available at Morgan Stanley Wealth Management

·Employer-sponsored retirement plans (e.g., 401(k) plans, 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans). For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans

·Morgan Stanley employee and employee-related accounts according to Morgan Stanley’s account linking rules

·Shares purchased through reinvestment of dividends and capital gains distributions when purchasing shares of the same fund

·Shares purchased through a Morgan Stanley self-directed brokerage account

·Class C (i.e., level-load) shares that are no longer subject to a contingent deferred sales charge and are converted to Class A shares of the same fund pursuant to Morgan Stanley Wealth Management’s share class conversion program

·Shares purchased from the proceeds of redemptions within the same fund family, provided (i) the repurchase occurs within 90 days following the redemption, (ii) the redemption and purchase occur in the same account, and (iii) redeemed shares were subject to a front-end or deferred sales charge.

Calvert Responsible Municipal Income Fund41Prospectus dated May 1, 2024

Fund Purchases through Raymond James & Associates, Inc., Raymond James Financial Services, Inc. and each entity’s affiliates (“Raymond James”)

Effective March 1, 2019, shareholders purchasing fund shares through a Raymond James platform or account, or through an introducing broker-dealer or independent registered investment adviser for which Raymond James provides trade execution, clearance, and/or custody services, will be eligible only for the following load waivers (front-end sales charge waivers and contingent deferred, or back-end, sales charge waivers) and discounts, which may differ from those disclosed elsewhere in this fund’s prospectus or SAI.

Front-end sales load waivers on Class A shares available at Raymond James

·Shares purchased in an investment advisory program.

·Shares purchased within the same fund family through a systematic reinvestment of capital gains and dividend distributions.

·Employees and registered representatives of Raymond James or its affiliates and their family members as designated by Raymond James.

·A shareholder in the Fund’s Class C shares will have their shares converted at net asset value to Class A shares (or the appropriate share class) of the Fund if the shares are no longer subject to a CDSC and the conversion is in line with the policies and procedures of Raymond James.

CDSC Waivers on Classes A and C shares available at Raymond James

·Death or disability of the shareholder.

·Shares sold as part of a systematic withdrawal plan as described in the fund’s prospectus.

·Return of excess contributions from an IRA Account.

·Shares sold as part of a required minimum distribution for IRA and retirement accounts due to the shareholder reaching the qualified age based on applicable IRS regulations as described in the fund’s prospectus.

·Shares sold to pay Raymond James fees but only if the transaction is initiated by Raymond James.

·Shares acquired through a right of reinstatement.

Front-end load discounts available at Raymond James: breakpoints, rights of accumulation, and/or letters of intent

·Breakpoints as described in this prospectus.

·Rights of accumulation which entitle shareholders to breakpoint discounts will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at Raymond James. Eligible fund family assets not held at Raymond James may be included in the calculation of rights of accumulation only if the shareholder notifies his or her financial advisor about such assets.

·Letters of intent which allow for breakpoint discounts based on anticipated purchases within a fund family, over a 13-month time period. Eligible fund family assets not held at Raymond James may be included in the calculation of letters of intent only if the shareholder notifies his or her financial advisor about such assets.

Calvert Responsible Municipal Income Fund42Prospectus dated May 1, 2024

Fund Purchases through Janney Montgomery Scott LLC (“Janney”)

Effective May 1, 2020, if you purchase fund shares through a Janney brokerage account, you will be eligible for the following load waivers (front-end sales charge waivers and contingent deferred sales charge (“CDSC”), or back-end sales charge waivers) and discounts, which may differ from those disclosed elsewhere in this fund’s Prospectus or SAI.

Front-end sales charge* waivers on Class A shares available at Janney

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same fund (but not any other fund within the fund family).

·Shares purchased by employees and registered representatives of Janney or its affiliates and their family members as designated by Janney.

·Shares purchased from the proceeds of redemptions within the same fund family, provided (1) the repurchase occurs within ninety (90) days following the redemption, (2) the redemption and purchase occur in the same account, and (3) redeemed shares were subject to a front-end or deferred sales load (i.e., right of reinstatement).

·Shares acquired through a right of reinstatement.

·Class C shares that are no longer subject to a contingent deferred sales charge and are converted to Class A shares of the same fund pursuant to Janney’s policies and procedures.

CDSC waivers on Class A and C shares available at Janney

·Shares sold upon the death or disability of the shareholder.

·Shares sold as part of a systematic withdrawal plan as described in the fund’s Prospectus.

·Shares purchased in connection with a return of excess contributions from an IRA account.

·Shares sold as part of a required minimum distribution for IRA and other retirement accounts if the redemption is taken in or after the year the shareholder reaches qualified age based on applicable IRS regulations.

·Shares sold to pay Janney fees but only if the transaction is initiated by Janney.

·Shares acquired through a right of reinstatement.

·Shares exchanged into the same share class of a different fund.

Front-end sales charge* discounts available at Janney: breakpoints, rights of accumulation and/or letters of intent

·Breakpoints as described in the fund’s Prospectus.

·Rights of accumulation (“ROA”), which entitle shareholders to breakpoint discounts, will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at Janney. Eligible fund family assets not held at Janney may be included in the ROA calculation only if the shareholder notifies his or her financial advisor about such assets.

·Letters of intent which allow for breakpoint discounts based on anticipated purchases within a fund family, over a 13-month time period. Eligible fund family assets not held at Janney Montgomery Scott may be included in the calculation of letters of intent only if the shareholder notifies his or her financial advisor about such assets.

* Also referred to as an “initial sales charge.”

Calvert Responsible Municipal Income Fund43Prospectus dated May 1, 2024

Fund Purchases through Oppenheimer & Co. Inc. (“Oppenheimer”)

Effective May 1, 2020, shareholders purchasing Fund shares through an Oppenheimer platform or account are eligible only for the following load waivers (front-end sales charge waivers and contingent deferred, or back-end, sales charge waivers) and discounts, which may differ from those disclosed elsewhere in this Fund’s prospectus or SAI.

Front-end Sales Load Waivers on Class A Shares available at Oppenheimer

·Employer-sponsored retirement, deferred compensation and employee benefit plans (including health savings accounts) and trusts used to fund those plans, provided that the shares are not held in a commission-based brokerage account and shares are held for the benefit of the plan.

·Shares purchased by or through a 529 Plan.

·Shares purchased through a Oppenheimer affiliated investment advisory program.

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same fund (but not any other fund within the fund family).

·A shareholder in the Fund’s Class C shares will have their shares converted at net asset value to Class A shares (or the appropriate share class) of the Fund if the shares are no longer subject to a contingent deferred sales charge (CDSC) and the conversion is in line with the policies and procedures of Oppenheimer.

·Employees and registered representatives of Oppenheimer or its affiliates and their family members.

·Directors or Trustees of the Fund, and employees of the Fund’s investment adviser or any of its affiliates, as described in this prospectus.

CDSC Waivers on A and C Shares available at Oppenheimer

·Death or disability of the shareholder.

·Shares sold as part of a systematic withdrawal plan as described in the Fund’s prospectus.

·Return of excess contributions from an IRA Account.

·Shares sold as part of a required minimum distribution for IRA and retirement accounts due to the shareholder reaching the qualified age based on IRS regulations as described in the prospectus.

·Shares sold to pay Oppenheimer fees but only if the transaction is initiated by Oppenheimer.

·Shares acquired through a right of reinstatement.

Front-end load Discounts Available at Oppenheimer: Breakpoints, Rights of Accumulation & Letters of Intent

·Breakpoints as described in this prospectus.

·Rights of Accumulation (ROA) which entitle shareholders to breakpoint discounts will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at Oppenheimer. Eligible fund family assets not held at Oppenheimer may be included in the ROA calculation only if the shareholder notifies his or her financial advisor about such assets.

Calvert Responsible Municipal Income Fund44Prospectus dated May 1, 2024

Policies Regarding Transactions through Edward D. Jones & Co., L.P. (“Edward Jones”)

The following information has been provided by Edward Jones:

Effective on or after January 1, 2024, the following information supersedes prior information with respect to transactions and positions held in fund shares through an Edward Jones system. Clients of Edward Jones (also referred to as “shareholders”) purchasing fund shares on the Edward Jones commission and fee-based platforms are eligible only for the following sales charge discounts (also referred to as “breakpoints”) and waivers, which can differ from discounts and waivers described elsewhere in the mutual fund prospectus or statement of additional information (“SAI”) or through another broker-dealer. In all instances, it is the shareholder's responsibility to inform Edward Jones at the time of purchase of any relationship, holdings of fund family, or other facts qualifying the purchaser for discounts or waivers. Edward Jones can ask for documentation from the shareholder of such circumstance. Shareholders should contact Edward Jones if they have questions regarding their eligibility for these discounts and waivers.

Breakpoints

·Breakpoint pricing, otherwise known as volume pricing, at dollar thresholds as described in the prospectus.

Rights of Accumulation (“ROA”)

·The applicable sales charge on a purchase of Class A shares is determined by taking into account all share classes (except certain money market funds and any assets held in group retirement plans) of the mutual fund family held by the shareholder or in an account grouped by Edward Jones with other accounts for the purpose of providing certain pricing considerations (“pricing groups”). If grouping assets as a shareholder, this includes all share classes held on the Edward Jones platform and/or held on another platform. The inclusion of eligible fund family assets in the ROA calculation is dependent on the shareholder notifying Edward Jones of such assets at the time of calculation. Money market funds are included only if such shares were sold with a sales charge at the time of purchase or acquired in exchange for shares purchased with a sales charge.

·The employer maintaining a SEP IRA plan and/or SIMPLE IRA plan may elect to establish or change ROA for the IRA accounts associated with the plan to a plan-level grouping as opposed to including all share classes at a shareholder or pricing group level.

·ROA is determined by calculating the higher of cost minus redemptions or market value (current shares x NAV).

Letter of Intent (“LOI”)

·Through a LOI, shareholders can receive the sales charge and breakpoint discounts for purchases shareholders intend to make over a 13-month period from the date Edward Jones receives the LOI. The LOI is determined by calculating the higher of cost or market value of qualifying holdings at LOI initiation in combination with the value that the shareholder intends to buy over a 13-month period to calculate the front-end sales charge and any breakpoint discounts. Each purchase the shareholder makes during that 13-month period will receive the sales charge and breakpoint discount that applies to the total amount. The inclusion of eligible fund family assets in the LOI calculation is dependent on the shareholder notifying Edward Jones of such assets at the time of calculation. Purchases made before the LOI is received by Edward Jones are not adjusted under the LOI and will not reduce the sales charge previously paid. Sales charges will be adjusted if LOI is not met.

·If the employer maintaining a SEP IRA plan and/or SIMPLE IRA plan has elected to establish or change ROA for the IRA accounts associated with the plan to a plan-level grouping, LOIs will also be at the plan-level and may only be established by the employer.

Sales Charge Waivers

Sales charges are waived for the following shareholders and in the following situations:

·Associates of Edward Jones and its affiliates and other accounts in the same pricing group (as determined by Edward Jones under its policies and procedures) as the associate. This waiver will continue for the remainder of the associate's life if the associate retires from Edward Jones in good-standing and remains in good standing pursuant to Edward Jones' policies and procedures.

·Shares purchased in an Edward Jones fee-based program.

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment.

·Shares purchased from the proceeds of redeemed shares of the same fund family so long as the following conditions are met: the proceeds are from the sale of shares within 60 days of the purchase, the sale and purchase are made from a share class that charges a front load and one of the following:

·The redemption and repurchase occur in the same account.

Calvert Responsible Municipal Income Fund45Prospectus dated May 1, 2024

·The redemption proceeds are used to process an: IRA contribution, excess contributions, conversion, recharacterizing of contributions, or distribution, and the repurchase is done in an account within the same Edward Jones grouping for ROA.

·Shares exchanged into Class A shares from another share class so long as the exchange is into the same fund and was initiated at the discretion of Edward Jones. Edward Jones is responsible for any remaining CDSC due to the fund company, if applicable. Any future purchases are subject to the applicable sales charge as disclosed in the prospectus.

·Exchanges from Class C shares to Class A shares of the same fund, generally, in the 84th month following the anniversary of the purchase date or earlier at the discretion of Edward Jones.

·Purchases of Class 529-A shares through a rollover from either another education savings plan or a security used for qualified distributions.

·Purchases of Class 529 shares made for recontribution of refunded amounts.

Contingent Deferred Sales Charge (“CDSC”) Waivers

If the shareholder purchases shares that are subject to a CDSC and those shares are redeemed before the CDSC is expired, the shareholder is responsible to pay the CDSC except in the following conditions:

·The death or disability of the shareholder.

·Systematic withdrawals with up to 10% per year of the account value.

·Return of excess contributions from an Individual Retirement Account (IRA).

·Shares redeemed as part of a required minimum distribution for IRA and retirement accounts if the redemption is taken in or after the year the shareholder reaches qualified age based on applicable IRS regulations.

·Shares redeemed to pay Edward Jones fees or costs in such cases where the transaction is initiated by Edward Jones.

·Shares exchanged in an Edward Jones fee-based program.

·Shares acquired through NAV reinstatement.

·Shares redeemed at the discretion of Edward Jones for Minimum Balances as described below.

Other Important Information Regarding Transactions Through Edward Jones

Minimum Purchase Amounts

·Initial purchase minimum: $250

·Subsequent purchase minimum: none

Minimum Balances

·Edward Jones has the right to redeem at its discretion fund holdings with a balance of $250 or less. The following are examples of accounts that are not included in this policy:

·A fee-based account held on an Edward Jones platform

·A 529 account held on an Edward Jones platform

·An account with an active systematic investment plan or LOI

Exchanging Share Classes

·At any time it deems necessary, Edward Jones has the authority to exchange at NAV a shareholder's holdings in a fund to Class A shares of the same fund.

Calvert Responsible Municipal Income Fund46Prospectus dated May 1, 2024

Fund Purchases through D.A. Davidson & Co. (“D.A. Davidson”)

Effective 5/1/2020, shareholders purchasing fund shares including existing fund shareholders through a D.A. Davidson platform or account, or through an introducing broker-dealer or independent registered investment advisor for which D.A. Davidson provides trade execution, clearance, and/or custody services, will be eligible for the following sales charge waivers (front-end sales charge waivers and contingent deferred, or back-end, sales charge waivers) and discounts, which may differ from those disclosed elsewhere in this prospectus or SAI.

Front-End Sales Charge Waivers on Class A Shares available at D.A. Davidson

·Shares purchased within the same fund family through a systematic reinvestment of capital gains and dividend distributions.

·Employees and registered representatives of D.A. Davidson or its affiliates and their family members as designated by D.A. Davidson.

·A shareholder in the Fund’s Class C shares will have their shares converted at net asset value to Class A shares (or the appropriate share class) of the Fund if the shares are no longer subject to a CDSC and the conversion is consistent with D.A. Davidson’s policies and procedures.

CDSC Waivers on Classes A and C shares available at D.A. Davidson

·Death or disability of the shareholder.

·Shares sold as part of a systematic withdrawal plan as described in the fund’s prospectus.

·Return of excess contributions from an IRA Account.

·Shares sold as part of a required minimum distribution for IRA or other qualifying retirement accounts as described in the fund’s prospectus beginning in the calendar year the shareholder turns age 72.

·Shares acquired through a right of reinstatement.

Front-end sales charge discounts available at D.A. Davidson: breakpoints, rights of accumulation and/or letters of intent CDSC Waivers on Classes A and C shares available at D.A. Davidson

·Breakpoints as described in this prospectus.

·Rights of accumulation which entitle shareholders to breakpoint discounts will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at D.A. Davidson. Eligible fund family assets not held at D.A. Davidson may be included in the calculation of rights of accumulation only if the shareholder notifies his or her financial advisor about such assets.

·Letters of intent which allow for breakpoint discounts based on anticipated purchases within a fund family, over a 13-month time period. Eligible fund family assets not held at D.A. Davidson may be included in the calculation of letters of intent only if the shareholder notifies his or her financial advisor about such assets.

Calvert Responsible Municipal Income Fund47Prospectus dated May 1, 2024

Fund Purchases through Robert W. Baird & Co. Incorporated (“Baird”)

Effective June 15, 2020, shareholders purchasing fund shares through a Baird platform or account will only be eligible for the following sales charge waivers (front-end sales charge waivers and CDSC waivers) and discounts, which may differ from those disclosed elsewhere in this prospectus or the SAI

Front-End Sales Charge Waivers on Class A shares Available at Baird

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment when purchasing share of the same fund

·Share purchase by employees and registers representatives of Baird or its affiliate and their family members as designated by Baird

·Shares purchase from the proceeds of redemptions within the same fund family, provided (1) the repurchase occurs within 90 days following the redemption, (2) the redemption and purchase occur in the same accounts, and (3) redeemed shares were subject to a front-end or deferred sales charge (known as rights of reinstatement)

·A shareholder in the Fund’s Class C Shares will have their shares converted at net asset value to Class A shares of the Fund if the shares are no longer subject to CDSC and the conversion is in line with the policies and procedures of Baird

·Employer-sponsored retirement plans or charitable accounts in a transactional brokerage account at Baird, including 401(k) plans, 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans. For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs or SAR-SEPs

CDSC Waivers on Class A and C shares Available at Baird

·Shares sold due to death or disability of the shareholder

·Shares sold as part of a systematic withdrawal plan as described in the Fund’s Prospectus

·Shares sold due to returns of excess contributions from an IRA Account

·Shares sold as part of a required minimum distribution for IRA and retirement accounts

·Shares sold to pay Baird fees but only if the transaction is initiated by Baird

·Shares acquired through a right of reinstatement

Front-End Sales Charge Discounts Available at Baird: Breakpoints and/or Rights of Accumulations

·Breakpoints as described in this prospectus

·Rights of accumulations which entitles shareholders to breakpoint discounts will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at Baird. Eligible fund family assets not held at Baird may be included in the rights of accumulations calculation only if the shareholder notifies his or her financial advisor about such assets

·Letters of Intent (LOI) allow for breakpoint discounts based on anticipated purchases of fund family assets through Baird, over a 13-month period of time

Calvert Responsible Municipal Income Fund48Prospectus dated May 1, 2024

Waivers Specific to Stifel, Nicolaus & Company, Incorporated (“Stifel”)

Effective July 1, 2020, shareholders purchasing Fund shares through a Stifel platform or account or who own shares for which Stifel or an affiliate is the broker-dealer of record are eligible for the following additional sales charge waiver:

Front-End Sales Load Waiver on Class A shares

·Class C shares that have been held for more than seven (7) years will be converted to Class A shares of the same Fund at net asset value pursuant to Stifel’s policies and procedures.

Calvert Responsible Municipal Income Fund49Prospectus dated May 1, 2024

Fund Purchases through J.P. Morgan Securities LLC

Effective September 29, 2023, if you purchase or hold fund shares through an applicable J.P. Morgan Securities LLC brokerage account, you will be eligible for the following sales charge waivers (front-end sales charge waivers and contingent deferred sales charge (“CDSC”), or back-end sales charge, waivers), share class conversion policy and discounts, which may differ from those disclosed elsewhere in this fund’s prospectus or Statement of Additional Information.

Front-end sales charge waivers on Class A shares available at J.P. Morgan Securities LLC

·Shares exchanged from Class C (i.e. level-load) shares that are no longer subject to a CDSC and are exchanged into Class A shares of the same fund pursuant to J.P. Morgan Securities LLC’s share class exchange policy.

·Qualified employer-sponsored defined contribution and defined benefit retirement plans, nonqualified deferred compensation plans, other employee benefit plans and trusts used to fund those plans. For purposes of this provision, such plans do not include SEP IRAs, SIMPLE IRAs, SAR-SEPs or 501(c)(3) accounts.

·Shares of funds purchased through J.P. Morgan Securities LLC Self-Directed Investing accounts.

·Shares purchased through rights of reinstatement.

·Shares purchased through reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same fund (but not any other fund within the fund family).

·Shares purchased by employees and registered representatives of J.P. Morgan Securities LLC or its affiliates and their spouse or financial dependent as defined by J.P. Morgan Securities LLC.

Class C to Class A share conversion

·A shareholder in the fund’s Class C shares will have their shares converted at net asset value by J.P. Morgan Securities LLC to Class A shares (or the appropriate share class) of the same fund if the shares are no longer subject to a CDSC and the conversion is consistent with J.P. Morgan Securities LLC’s policies and procedures.

CDSC waivers on Class A and C shares available at J.P. Morgan Securities LLC

·Shares sold upon the death or disability of the shareholder.

·Shares sold as part of a systematic withdrawal plan as described in the fund’s prospectus.

·Shares purchased in connection with a return of excess contributions from an IRA account.

·Shares sold as part of a required minimum distribution for IRA and retirement accounts pursuant to the Internal Revenue Code.

·Shares acquired through a right of reinstatement.

Front-end load discounts available at J.P. Morgan Securities LLC: breakpoints, rights of accumulation & letters of intent

·Breakpoints as described in the prospectus.

·Rights of Accumulation (“ROA”) which entitle shareholders to breakpoint discounts as described in the fund’s prospectus will be automatically calculated based on the aggregated holding of fund family assets held by accounts within the purchaser’s household at J.P. Morgan Securities LLC. Eligible fund family assets not held at J.P. Morgan Securities LLC (including 529 program holdings, where applicable) may be included in the ROA calculation only if the shareholder notifies their financial advisor about such assets.

·Letters of Intent (“LOI”) which allow for breakpoint discounts based on anticipated purchases within a fund family, through J.P. Morgan Securities LLC, over a 13-month period of time (if applicable).

Calvert Responsible Municipal Income Fund50Prospectus dated May 1, 2024

More Information

About the Fund: More information is available in the Statement of Additional Information. The Statement of Additional Information is incorporated by reference into this Prospectus. Additional information about the Fund’s investments is available in the annual and semiannual reports (collectively, the “reports”). In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during the past fiscal year. You may obtain free copies of the Statement of Additional Information and the reports on Calvert’s website at www.calvert.com or by contacting the principal underwriter:

Eaton Vance Distributors, Inc.
One Post Office Square
Boston, MA 02109
1-800-368-2745
website: www.calvert.com

Information about the Fund (including the Statement of Additional Information and reports) is available on the EDGAR database on the SEC’s website at www.sec.gov, and copies of this information may be obtained, after paying a duplicating fee, by electronic request at the following email address: publicinfo@sec.gov.

As permitted by regulations adopted by the Securities and Exchange Commission, paper copies of the Fund’s annual and semi-annual shareholder reports are no longer being sent by mail unless you specifically request paper copies of the reports. Instead, the reports are being made available on the Fund’s website (http://www.calvert.com/prospectus), and you will be notified each time a report is posted and provided with a website address to access the report. You may elect to receive all future Fund shareholder reports in paper free of charge at any time. If you are a direct investor, you can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by calling 1-800- 368-2745. If you own these shares through a financial intermediary, you must contact your financial intermediary to elect to continue to receive paper copies of your shareholder reports. If you are a direct investor, you may elect to receive shareholder reports and other communications from the Fund electronically by signing up for e-Delivery at calvert.com. If you own your shares through a financial intermediary (such as a broker-dealer or bank), you must contact your financial intermediary to sign up.

Shareholder Inquiries: You can obtain more information from Calvert Shareholder Services or the Fund transfer agent, SS&C GIDS, Inc. If you own shares and would like to add to, redeem from or change your account, please write or call below:

Regular Mailing Address:
Calvert Funds
P.O. Box 219544
Kansas City, MO 64121-9544

Overnight Mailing Address:
Calvert Funds
430 West 7th Street
Kansas City, MO 64105-1407

Phone Number:
1-800-368-2745
Monday – Thursday
9:00 a.m. – 5:30 p.m. ET
Friday
9:00 a.m. – 5:00 p.m. ET

The Fund's Investment Company Act No. is 811-03101.
24169 5.1.24	© 2024 Calvert Research and Management

Printed on recycled paper.

Calvert Emerging Markets Focused Growth Fund

Class A Shares - CEMAX Class C Shares - CEMCX Class I Shares - CMEIX Class R6 Shares - CMERX

Prospectus Dated
May 1, 2024

The Securities and Exchange Commission (“SEC”) has not approved or disapproved these securities or determined if this Prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Information in this Prospectus

	Page		Page
Fund Summary	2	Investment Objective & Principal Policies and Risks	8
Investment Objective	2	About Responsible Investing	20
Fees and Expenses of the Fund	2	Management and Organization	21
Portfolio Turnover	2	Valuing Shares	22
Principal Investment Strategies	3	Purchasing Shares	23
Principal Risks	3	Sales Charges	28
Performance	6	Redeeming Shares	30
Management	6	Shareholder Account Features	31
Purchase and Sale of Fund Shares	6	Potential Conflicts of Interest	33
Tax Information	6	Additional Tax Information	35
Payments to Broker-Dealers and Other Financial Intermediaries	7	Financial Highlights	37
		Appendix A – The Calvert Principles for Responsible Investment	38
		Appendix B – Financial Intermediary Sales Charge Variations	40

This Prospectus contains important information about the Fund and the services
available to shareholders. Please save it for reference.

Fund Summary

Investment Objective

The Fund's investment objective is total return.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. Investors may also pay commissions or other fees to their financial intermediary, which are not reflected below. You may qualify for a reduced sales charge on purchases of Class A shares if you invest, or agree to invest over a 13-month period, at least $50,000 in Calvert funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix B – Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial intermediary and under “Sales Charges” on page 28 of this Prospectus and page 17 of the Fund’s Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)	Class A	Class C	Class I	Class R6
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.25%	None	None	None
Maximum Deferred Sales Charge (load) (as a percentage of the lower of net asset value at purchase or redemption)	None(1)	1.00%	None	None

(1)Class A shares purchased at net asset value in amounts of $1 million or more are subject to a 1.00% contingent deferred sales charge if redeemed within 12 months of purchase.

Annual Fund Operating Expenses (expenses you pay each year as a percentage of the value of your investment)	Class A	Class C	Class I	Class R6
Management Fees	0.87%	0.87%	0.87%	0.87%
Distribution and Service (12b-1) Fees	0.25%	1.00%	None	None
Other Expenses (1)	4.52%	4.52%	4.52%	4.52%
Total Annual Fund Operating Expenses	5.64%	6.39%	5.39%	5.39%
Less Expense Reimbursement and Fee Reduction (2)	(4.40)%	(4.40)%	(4.40)%	(4.40)%
Net Annual Fund Operating Expenses	1.24%	1.99%	0.99%	0.99%

(1)Based on estimates for the current fiscal year.

(2)Calvert Research and Management (“CRM”) has agreed to reimburse the Fund’s expenses to the extent that Total Annual Fund Operating Expenses exceed 1.24% for Class A shares, 1.99% for Class C shares, 0.99% for Class I shares and 0.99% for Class R6 shares. This expense reimbursement will continue through May 1, 2025. Any amendment to or termination of this reimbursement would require approval of the Board of Trustees. The expense reimbursement relates to ordinary operating expenses only and does not include expenses such as: brokerage commissions, acquired fund fees and expenses of unaffiliated funds, borrowing costs (including borrowing costs of any acquired funds), taxes or litigation expenses. Amounts reimbursed may be recouped by CRM during the same fiscal year to the extent actual expenses are less than any contractual expense cap in place during such year. Pursuant to this arrangement, CRM may recoup from the Fund any reimbursed expenses during the same fiscal year if such recoupment does not cause the Fund’s Total Annual Operating Expenses after such recoupment to exceed (i) the expense limit in effect at the time of reimbursement; or (ii) the expense limit in effect at the time of recoupment.

Example. This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, that the operating expenses remain the same and that any expense reimbursement arrangement remains in place for the contractual period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	Expenses with Redemption				Expenses without Redemption
	1 Year	3 Years	5 Years	10 Years	1 Year	3 Years	5 Years	10 Years
Class A shares	$645	$1,747	$2,834	$5,494	$645	$1,747	$2,834	$5,494
Class C shares	$302	$1,500	$2,763	$5,638	$202	$1,500	$2,763	$5,638
Class I shares	$101	$1,218	$2,326	$5,059	$101	$1,218	$2,326	$5,059
Class R6 shares	$101	$1,218	$2,326	$5,059	$101	$1,218	$2,326	$5,059

Calvert Emerging Markets Focused Growth Fund2Prospectus dated May 1, 2024

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the period May 31, 2023 (commencement of operations) to December 31, 2023, the Fund's portfolio turnover rate was 29% of the average value of its portfolio.

Principal Investment Strategies

Under normal market conditions, at least 80% of the Fund’s assets (plus any borrowings for investment purposes) will be invested in equity securities of companies located in emerging market countries. The Fund is sub-advised by Morgan Stanley Investment Management Company (the “Sub-Adviser”).

The Sub-Adviser seeks to construct a focused portfolio of approximately 40 to 60 equity securities designed to take advantage of thematic opportunities in emerging markets. The Sub-Adviser seeks to invest in companies that it believes have the potential to outperform emerging markets generally over the long-term and which meet the responsible investing criteria described below.

The Sub-Adviser considers an issuer to be located in an emerging market country if (i) its principal securities trading market is in an emerging market country; (ii) alone or on a consolidated basis it derives 50% or more of its annual revenue or profits from goods produced, sales made or services performed in emerging market countries or has at least 50% of its assets, core business operations and/or employees in emerging markets countries; or (iii) it is organized under the laws of, or has a principal office in, an emerging market country. By applying this test, it is possible that a particular issuer could be deemed to be located in more than one country.

Emerging market or developing countries are countries that major international financial institutions generally consider to be less economically mature than developed nations, such as the United States, Canada, Japan, Australia, New Zealand and most countries located in Western Europe (such as the United Kingdom and France) or are countries included in the Fund’s benchmark, MSCI Emerging Markets Index. The specific countries that comprise emerging markets or developing countries may change from time to time.

The Fund may invest in all types of equity securities, including common and preferred stocks, convertible securities, rights, warrants, depositary receipts, limited partnership interests and other specialty securities having equity features. The Fund may hold or have exposure to equity securities of companies of any size, including small and medium capitalization companies, and to companies in any industry or sector. At times, the Fund’s investments may be focused in one or more sectors.

The Fund also may invest in American Depositary Receipts (“ADRs”), which are either sponsored or unsponsored, Global Depositary Receipts (“GDRs”) and other types of depositary receipts with respect to companies located in emerging market countries, and such investments will represent equity securities of companies located in emerging market countries for purposes of maintaining exposure of at least 80% of the Fund's assets to such securities.

The Fund may, but it is not required to, use derivative instruments for a variety of purposes, including hedging, risk management or portfolio management. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as options, futures, swaps, contracts for difference (“CFDs”), structured investments and other related instruments and techniques. The Fund may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Fund will be counted toward the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy. The Fund may lend securities. The Fund may also seek to gain exposure to common stocks through the use of equity-linked securities (such as participation notes (“p-notes”)). The Fund expects to use p-notes to invest indirectly in certain stocks that trade in a market that restricts foreign investors, such as the Fund, from investing directly in the market.

The Sub-Adviser generally uses a fundamental bottom-up stock selection process informed by macro thematic research on overall emerging markets. The Sub-Adviser will employ this consistent and targeted approach seeking companies they expect to become leading companies in emerging markets as well as developed country domiciled companies where a large portion of the companies’ growth is taking place in emerging market countries. The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in the securities of a single issuer than a fund that is “diversified.”

Responsible Investing. The portfolio manager seeks to invest in companies that manage environmental, social and governance (“ESG”) risk exposures adequately and that are not exposed to excessive ESG risk through their principal business activities. Companies are analyzed by the investment adviser’s ESG analysts utilizing The Calvert Principles for

Calvert Emerging Markets Focused Growth Fund3Prospectus dated May 1, 2024

Responsible Investment (“Principles”), a framework for considering ESG factors (a copy of which is included as an appendix to the Fund’s Prospectus). Each company is evaluated relative to an appropriate peer group based on material ESG factors as determined by the investment adviser. Pursuant to the Principles, the investment adviser seeks to identify companies and other issuers that operate in a manner that is consistent with or promotes environmental sustainability and resource efficiency, equitable societies and respect for human rights, and accountable governance and transparency. The Fund generally invests in issuers that are believed by the investment adviser to operate in accordance with the Principles and may also invest in issuers that the investment adviser believes are likely to operate in accordance with the Principles pending the investment adviser’s engagement activity with such issuer.

Principal Risks

Equity Securities Risk. The value of equity securities and related instruments may decline in response to adverse changes in the economy or the economic outlook; deterioration in investor sentiment; interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer and sector-specific considerations; unexpected trading activity among retail investors; or other factors. Market conditions may affect certain types of stocks to a greater extent than other types of stocks. If the stock market declines in value, the value of the Fund’s equity securities will also likely decline. Although prices can rebound, there is no assurance that values will return to previous levels.

Emerging Markets Investment Risk. Investment markets within emerging market countries are typically smaller, less liquid, less developed and more volatile than those in more developed markets like the United States, and may be focused in certain sectors. Emerging market securities often involve greater risks than developed market securities. The information available about an emerging market issuer may be less reliable than for comparable issuers in more developed capital markets.

Foreign Investment Risk. Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country against a particular country or countries, organizations, entities and/or individuals. There may be less publicly available information about foreign issuers because they may not be subject to reporting practices, requirements or regulations comparable to those to which United States companies are subject. Adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States and, as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund may have difficulties enforcing its legal or contractual rights in a foreign country. Depositary receipts are subject to many of the risks associated with investing directly in foreign instruments, including the political and economic risks of the underlying issuer's country and, in the case of depositary receipts traded on foreign markets, currency risk.

China Region Risk. Economies of countries in the China region differ from the U.S. economy in various ways, such as structure, general development, government involvement, wealth distribution, interest rates, rate of growth of gross national product, rate of inflation, capital reinvestment, resource self-sufficiency and balance of payments position. As export-driven economies, the economies of countries in the China region are affected by developments in the economies and governmental actions of their principal trading partners, such as the imposition of trading restrictions and tariffs. China’s governmental actions and the actions of other governments located in the region can have a significant effect on the economic conditions in the China region or a particular issuer or industry, which could adversely affect the value and liquidity of investments. For example, a government may restrict investment in companies or industries considered important to national interests, intervene in the financial markets, maintain strict currency controls, or impose repatriation restrictions. Significant portions of the Chinese securities markets may become rapidly illiquid, as Chinese issuers may suspend the trading of their equity securities. In addition, there is the potential of increased tariffs and restrictions on trade between the U.S. and China. An increase in tariffs or trade restrictions, or even the threat of such developments, could lead to a significant reduction in international trade, which could have a negative impact on the Fund. Although China and

Calvert Emerging Markets Focused Growth Fund4Prospectus dated May 1, 2024

certain other countries in the China region may be larger and/or more established than many emerging markets, markets in these countries carry the high levels of risk associated with emerging markets.

Geographic Risk. Because the Fund may invest significantly in a particular graphic region or country, the value of Fund shares may be affected by events that adversely affect that region or country and may fluctuate more than that of a fund that invests more broadly.

Currency Risk. Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

Smaller and Mid-Sized Company Risk. The stocks of smaller and mid-sized companies are generally subject to greater price fluctuations, limited liquidity, higher transaction costs and higher investment risk than the stocks of larger, more established companies. Such companies may have limited product lines, markets or financial resources, may be dependent on a limited management group, and may lack substantial capital reserves or an established performance record. There may be generally less publicly available information about such companies than for larger, more established companies. Stocks of these companies frequently have lower trading volumes making them more volatile and potentially less liquid and more difficult to value.

Frontier Market Investment Risk. Frontier markets are among the smallest and least mature investment markets. Frontier market countries may have greater political or economic instability and may also be subject to trade barriers, adjustments in currency values and developing or changing securities laws and other regulations. Investments in frontier market countries generally are less liquid and subject to greater price volatility than investments in developed markets or emerging markets.

Preferred Stock Risk. Although preferred stocks represent an ownership interest in an issuer, preferred stocks generally do not have voting rights or have limited voting rights and have economic characteristics similar to fixed-income securities. Preferred stocks are subject to issuer-specific risks generally applicable to equity securities and credit and interest rate risks generally applicable to fixed-income securities. The value of preferred stock generally declines when interest rates rise and may react more significantly than bonds and other debt instruments to actual or perceived changes in the company’s financial condition or prospects.

Participation Note Risk. Participation notes (“P-Notes”) are subject to the risks normally associated with a direct investment in the foreign securities underlying the P-Notes. As the purchaser of a P-Note, the Fund is relying on the creditworthiness of the counterparty issuing the P-Note and does not have the same rights under the P-Note as it would as the owner of the underlying security. If the counterparty becomes insolvent, the Fund could lose the total value of its investment in the P-Note. In addition, there is no assurance that there will be a trading market for a P-Note or that the trading price of a P-Note will equal the value of the underlying security.

Calvert Emerging Markets Focused Growth Fund5Prospectus dated May 1, 2024

Information Technology Sector Risk. The value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not concentrate in companies in the technology sector.

Issuer Non-Diversification Risk. The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in the securities of a single issuer than a fund that is “diversified.” Non-diversified funds may focus their investments in a small number of issuers, making them more susceptible to risks affecting such issuers than a more diversified fund might be, and the value of the Fund's shares may be more volatile than the values of shares of more diversified funds.

Calvert Emerging Markets Focused Growth Fund6Prospectus dated May 1, 2024

Performance

Performance history will be available for the Fund after the Fund has been in operation for one full calendar year. Updated Fund performance information can be obtained by visiting www.calvert.com. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future.

Management

Investment Adviser. Calvert Research and Management (“CRM” or the “Adviser”).

Investment Sub-Adviser. Morgan Stanley Investment Management Company (“MSIM Company”).

Portfolio Manager

Vishal Gupta, Managing Director of MSIM Company, has managed the Fund since its inception on December 21, 2022.

Purchase and Sale of Fund Shares

You may purchase, redeem or exchange Fund shares on any business day, which is any day the New York Stock Exchange is open for business. You may purchase, redeem or exchange Fund shares either through your financial intermediary or (except for purchases of Class C shares by accounts with no specified financial intermediary) directly from the Fund either by writing to the Fund, P.O. Box 219544, Kansas City, MO 64121-9544, or by calling 1-800-368-2745. The minimum initial purchase or exchange into the Fund is $1,000 for Class A and Class C, $1,000,000 for Class I and $5,000,000 for Class R6 (waived in certain circumstances). There is no minimum for subsequent investments.

Tax Information

If your shares are held in a taxable account, the Fund’s distributions will be taxed to you as ordinary income and/or capital gains, unless you are exempt from taxation. If your shares are held in a tax-advantaged account, you will generally be taxed only upon withdrawals from the account.

Payments to Broker-Dealers and Other Financial Intermediaries

Calvert Emerging Markets Focused Growth Fund7Prospectus dated May 1, 2024

Investment Objective & Principal Policies and Risks

Equity Securities. Equity securities include: common stocks; preferred stocks, including convertible and contingent convertible preferred stocks; equity interests in trusts, partnerships, joint ventures and other unincorporated entities or enterprises; depositary receipts, rights and warrants in underlying equity interests; and other securities that are treated as equity for U.S. federal income tax purposes. The Fund cannot predict the income it might receive from equity securities because issuers generally have discretion as to the payment of any dividends or distributions.

The value of equity securities and related instruments may decline in response to adverse changes in the economy or the economic outlook; deterioration in investor sentiment; interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions may affect certain types of stocks to a greater extent than other types of stocks. If the stock market declines, the value of Fund shares will also likely decline. Although stock prices can rebound, there is no assurance that values will return to previous levels.

Emerging Markets Investments. The risks of foreign investments can be more significant in emerging markets. Unless otherwise provided in the Fund’s principal investment strategies, an emerging market country is any country determined by the investment adviser to have an emerging market economy, considering factors such as the country’s political and economic stability, and the development of its financial and capital markets. Emerging markets may offer higher potential for gains and losses than investments in the developed markets of the world. Political and economic structures in emerging market countries generally lack the social, political and economic stability of developed countries, which may affect the value of the Fund’s investments in these countries and also the ability of the Fund to access markets in such countries. Securities markets within emerging market countries may experience low or non-existent trading volume, resulting in a lack of liquidity and increased volatility in prices for such securities, as compared to securities of comparable issuers in more developed capital markets. Emerging markets investments may also include investments through complex structures that may lack transparency.

Governmental actions can have a significant effect on the economic conditions in emerging market countries, which also may adversely affect the value and liquidity of the Fund’s investments. In particular, trade disputes may result in governmental actions that could have an adverse effect on investments in emerging market countries, including but not limited to restrictions on investments in, or required divestment of, particular issuers or industries. Such actions may effectively restrict or eliminate the Fund's ability to purchase or sell investments in emerging market countries, and thus may make them less liquid or more difficult to value, or may force the Fund to sell or otherwise dispose of such investments at inopportune times or prices.

There may be less publicly available information about issuers in emerging markets than would be available about issuers in more developed capital markets, and such issuers may not be subject to accounting, auditing and financial reporting standards and requirements comparable to those to which U.S. companies are subject. The laws of emerging market countries relating to the limited liability of corporate shareholders, fiduciary duties of officers and directors, and bankruptcy of state enterprises are generally less developed than or different from such laws in the United States. It may be more difficult to make a claim or obtain a judgment in the courts of these countries than it is in the United States. In addition, due to jurisdictional limitations, U.S. authorities (e.g., SEC and the U.S. Department of Justice) may be limited in their ability to enforce regulatory or legal obligations in emerging market countries. The possibility of fraud, negligence, undue influence being exerted by an issuer or refusal to recognize ownership exists in some emerging markets. The prices at which investments may be acquired may be affected by trading by persons with information that is not publicly available and by securities transactions by brokers in anticipation of transactions in particular securities. Disruptions due to work stoppages and trading improprieties in foreign securities markets have caused such markets to close. If extended closings were to occur in stock markets where the Fund is heavily invested, the Fund’s ability to redeem Fund shares could become impaired. In such circumstances, the Fund may have to sell more liquid securities than it would otherwise choose to sell. Emerging market securities are also subject to speculative trading, which contributes to their volatility.

Calvert Emerging Markets Focused Growth Fund8Prospectus dated May 1, 2024

Foreign Investments. Investments in foreign issuers could be affected by factors not present in the United States, including expropriation, armed conflict, confiscatory taxation, lack of uniform accounting and auditing standards, less publicly available financial and other information, and potential difficulties in enforcing contractual obligations. Because foreign issuers may not be subject to uniform accounting, auditing and financial reporting standard practices and requirements and regulatory measures comparable to those in the United States, there may be less publicly available information about such foreign issuers. Adverse changes in investment regulations, capital requirements or exchange controls could adversely affect the value of the Fund's investments. Settlements of securities transactions in foreign countries are subject to risk of loss, may be delayed and are generally less frequent than in the United States, which could affect the liquidity of the Fund’s assets. Evidence of ownership of certain foreign investments may be held outside the United States, and the Fund may be subject to the risks associated with the holding of such property overseas. Trading in certain foreign markets is also subject to liquidity risk.

Foreign investment in the securities markets of certain foreign countries is restricted or controlled to varying degrees. Foreign issuers may become subject to sanctions imposed by the United States or another country against a particular country or countries, organizations, entities and/or individuals, which could result in the immediate freeze of the foreign issuers’ assets or securities. The imposition of such sanctions could impair the market value of the securities of such foreign issuers and limit the Fund’s ability to buy, sell, receive or deliver the securities. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices, which could result in losses to the Fund and increased transaction costs. If a deterioration occurs in a country's balance of payments, the country could impose temporary restrictions on foreign capital remittances. The Fund could also be adversely affected by delays in, or a refusal to grant, any required governmental approval for repatriation, as well as by other restrictions on investment. The risks posed by such actions with respect to a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets. Even if the Fund does not have significant investments in securities affected by sanctions, sanctions or the threat of sanctions may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, including through global supply chain disruptions, increased inflationary pressures, and reduced economic activity, which could have a negative effect on the Fund’s performance. In addition, trade disputes may affect investor and consumer confidence and adversely affect financial markets and the broader economy, perhaps suddenly and to a significant degree. Events such as these and their impact on the Fund are difficult to predict.

In some non-U.S. securities markets, custody arrangements for securities provide significantly less protection than custody arrangements in U.S. securities markets, and prevailing custody and trade settlement practices (e.g., the requirement to pay for securities prior to receipt) expose the Fund to credit and other risks it does not have in the United States.

The Fund needs a license to invest directly in securities traded in many non-U.S. securities markets. These licenses are often subject to limitations, including maximum investment amounts. Once a license is obtained, the Fund's ability to continue to invest directly is subject to the risk that the license may be terminated or suspended. In some circumstances, the receipt of a non-U.S. license by one of CRM's clients may prevent the Fund from obtaining a similar license. In addition, certain activities could cause the suspension or revocation of the Fund's license.

Political events in foreign countries may cause market disruptions. In June 2016, the United Kingdom (“UK”) voted in a referendum to leave the European Union (“EU”) (“Brexit”). Effective January 31, 2020, the UK ceased to be a member of the EU and, following a transition period during which the EU and the UK Government engaged in a series of negotiations regarding the terms of the UK’s future relationship with the EU, the EU and the UK Government signed an agreement regarding the economic relationship between the UK and the EU. Market uncertainty remains regarding Brexit’s ramifications, and the range and potential implications of the possible political, regulatory, economic, and market outcomes in the UK, EU and beyond are difficult to predict. If one or more additional countries leave the EU or the EU dissolves, the world’s securities markets likely will be significantly disrupted.

In addition, the Holding Foreign Companies Accountable Act (the “HFCAA”) could cause securities of a foreign (non-U.S.) company, including American Depositary Receipts (“ADRs”), to be delisted from U.S. stock exchanges if the company does not allow the U.S. government to oversee the auditing of its financial information. Although the requirements of the HFCAA apply to securities of all foreign (non-U.S.) issuers, the SEC has thus far limited its enforcement efforts to securities of Chinese companies. If securities are delisted, the Fund’s ability to transact in such securities will be impaired, and the liquidity and market price of the securities may decline. The Fund may also need to seek other markets in which to transact in such securities, which could increase the Fund’s costs.

Calvert Emerging Markets Focused Growth Fund9Prospectus dated May 1, 2024

alternatives to directly purchasing the underlying foreign securities in their national markets and currencies. However, they continue to be subject to many of the risks associated with investing directly in foreign securities. These risks include the political and economic risks of the underlying issuer’s country, as well as in the case of depositary receipts traded on foreign markets, currency risk. Depositary receipts may be sponsored or unsponsored. Unsponsored depositary receipts are established without the participation of the issuer. As a result, available information concerning the issuer of an unsponsored depository receipt may not be as current as for sponsored depositary receipts, and the prices of unsponsored depositary receipts may be more volatile than if such instruments were sponsored by the issuer. Unsponsored depositary receipts may involve higher expenses, may not pass through voting or other shareholder rights and may be less liquid. Unless otherwise stated in the Fund Summary, such investments are not subject to any stated limitation on investing in foreign securities.

Investments in the China Region. Economies of countries in the China region differ from the U.S. economy in various ways, such as structure, general development, government involvement, wealth distribution, interest rates, rate of growth of gross national product, rate of inflation, capital reinvestment, resource self-sufficiency and balance of payments position. As export-driven economies, the economies of countries in the China region are affected by developments in the economies and government actions of their principal trading partners, such as the imposition of trading restrictions. Although larger and/or more established than many emerging markets, markets in the China region carry the high levels of risk associated with emerging markets including, among others, greater political, economic and social instability, market volatility caused by potential regional or territorial conflicts or natural disasters (such as monsoons), and price volatility and a lack of liquidity in securities. Accounting, auditing, financial, and other reporting standards, practices and disclosure requirements in China are different, sometimes in fundamental ways, from those in the United States and certain Western European countries. For example, financial reporting for companies domiciled in China does not have as much regulatory oversight as reporting for companies in the United States. Consequently, investments in the China region are subject to the risk of confiscatory taxation, nationalization or expropriation of assets, potentially frequent changes in the law, and imperfect information.

China’s governmental actions and the actions of other governments can have a significant effect on the economic conditions in the China region, which could adversely affect the value and liquidity of investments. The Chinese central government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation and/or state ownership and actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China. For example, the Chinese government may restrict investment in companies or industries considered important to national interests, or intervene in the financial markets, such as by imposing trading restrictions, or banning or curtailing short selling. In addition, the Chinese government has from time to time taken actions that influence the prices at which certain goods may be sold, encourage companies to invest or concentrate in particular industries, induce mergers between companies in certain industries and induce private companies to publicly offer their securities to increase or continue the rate of economic growth, control the rate of inflation or otherwise regulate economic expansion. It may do so in the future as well, potentially having a significant adverse effect on economic conditions in the China region.

The Chinese government also maintains strict currency controls and imposes repatriation restrictions in order to achieve economic, trade and political objectives and regularly intervenes in the currency market. The imposition of currency controls and repatriation restrictions may negatively impact the performance and liquidity of the Fund as capital may become trapped in the China region. Chinese yuan currency exchange rates can be very volatile and can change quickly and unpredictably. Although the Chinese government has begun to institute legal and economic reform policies, there can be no assurances that it will continue to pursue such policies or, if it does, that such policies will succeed.

The Chinese securities markets are emerging markets characterized by greater price volatility relative to U.S. markets. Liquidity risks may be more pronounced for the A-share market than for Chinese securities markets generally because the A-share market is subject to greater government restrictions and control. The A-share market is generally volatile, and the risks of investing include possible government intervention, as well as the risk that securities on the A-share market may be suspended from trading without an indication of how long the suspension will last, which may impair the liquidity of such securities. Price fluctuations of A-shares are limited per trading day. In addition, there is less regulation and monitoring of Chinese securities markets and the activities of investors, brokers and other participants than in the United States.

Calvert Emerging Markets Focused Growth Fund10Prospectus dated May 1, 2024

could lead to a significant reduction in international trade, which could have a negative impact on the Fund. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth in China. In addition, each of Hong Kong’s and Taiwan’s evolving relationship with the central government in Beijing has been a source of political unrest and may result in economic disruption.

Foreign Currencies. The value of foreign assets and currencies as measured in U.S. dollars may be affected favorably or unfavorably by changes in foreign currency rates and exchange control regulations, application of foreign tax laws (including withholding tax), governmental administration of economic or monetary policies (in this country or abroad), and relations between nations and trading. Foreign currencies also are subject to settlement, custodial and other operational risks. Currency exchange rates can be affected unpredictably by intervention, or the failure to intervene, by U.S. or foreign governments or central banks or by currency controls or political developments in the United States or abroad. If the U.S. dollar rises in value relative to a foreign currency, a security denominated in that foreign currency will be worth less in U.S. dollars. If the U.S. dollar decreases in value relative to a foreign currency, a security denominated in that foreign currency will be worth more in U.S. dollars. A devaluation of a currency by a country’s government or banking authority will have a significant impact on the value of any investments denominated in that currency. Costs are incurred in connection with conversions between currencies.

The Fund may engage in spot transactions and forward foreign currency exchange contracts, purchase and sell options on currencies and purchase and sell currency futures contracts and related options thereon (collectively, “Currency Instruments”) to seek to hedge against the decline in the value of currencies in which its portfolio holdings are denominated against the U.S. dollar.

Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect programs (“Stock Connect”), which allow non-Chinese investors (such as the Fund) to purchase certain listed equities via brokers in Hong Kong, Stock Connect, or on such other stock exchanges in China that participate in Stock Connect from time to time. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns.

Variable Interest Entities. The Fund may gain economic exposure to certain operating companies in China through legal structures known as variable interest entities (“VIEs”). From time to time, the Fund’s investments in U.S.-listed shell companies relying on VIE structures to consolidate China-based operations may be significant. In a VIE structure, a China-based operating company (“Operating Company”) typically establishes an offshore shell company (“Shell Company”) in another jurisdiction, such as the Cayman Islands, which then enters into service and other contracts with the Operating Company and issues shares on a foreign exchange, like the New York Stock Exchange or Hong Kong Exchange. Investors in VIEs hold stock in the Shell Company rather than directly in the Operating Company and the Shell Company may not own stock or other equity in the Operating Company. Certain Chinese companies have used VIEs to facilitate foreign investment because of Chinese governmental prohibitions or restrictions on non-Chinese ownership (e.g., by U.S. persons and entities such as the Fund) of companies in certain industries in China. Through a VIE arrangement, the Operating Companies indirectly raise capital from U.S. investors without distributing ownership of the Operating Companies to U.S. investors.

Investments in VIEs are subject to risks in addition to those generally associated with investments in China. For example, breaches of the contractual arrangements, changes in Chinese law with respect to enforceability or permissibility of these arrangements or failure of these contracts to function as intended would likely adversely affect an investment in a VIE. In addition, VIEs are also subject to the risk of inconsistent and unpredictable application of Chinese law, that the Shell Company may lose control over the Operating Company and that the equity owners of the Operating Company may have interests conflicting with those of the Shell Company’s investors. There is also uncertainty related to the Chinese taxation of VIEs and the Chinese tax authorities may take positions which result in increased tax liabilities. Thus, investors, such as the Fund, face risks and uncertainty about future actions or intervention by the government of China at any time and without notice that could suddenly and significantly affect VIEs and the enforceability of the Shell Company’s contractual arrangements with the Operating Company. If these risks materialize, the value of investments in VIEs could be significantly adversely affected and the Fund could incur significant losses with no recourse available.

H-Shares Risk. H-shares are foreign securities which, in addition to the risks described herein, are subject to the risk that the Hong Kong stock market may behave very differently from the mainland Chinese stock market. There may be little to no correlation between the performance of the Hong Kong stock market and the mainland Chinese stock market.

Calvert Emerging Markets Focused Growth Fund11Prospectus dated May 1, 2024

Red Chip Companies Risk. Red Chip company shares are traded in Hong Kong dollars on the Hong Kong Stock Exchange and may also be traded by foreigners. Because Red Chip companies are substantially controlled by various Chinese governmental authorities, investing in Red Chip companies involves risks that political changes, social instability, regulatory uncertainty, adverse diplomatic developments, asset expropriation or nationalization, or confiscatory taxation could adversely affect the performance of Red Chip companies. Red Chip companies may be less efficiently run and less profitable than other companies.

Smaller Companies. Securities of smaller companies, which may include legally restricted securities, are generally subject to greater price fluctuations, limited liquidity, higher transaction costs and higher investment risk than the securities of larger, more established companies. Such companies may have limited product lines, markets or financial resources, may be dependent on a limited management group, and may lack substantial capital reserves or an established performance record. There may be generally less publicly available information about such companies than for larger, more established companies. Because of the absence of any public trading market for some of these investments (such as those which are legally restricted) it may be more difficult to value these investments and may take longer to liquidate these positions at fair value than would be the case for publicly traded securities.

Frontier Market Investments. Because frontier markets are among the smallest, least mature and least liquid markets, investments in frontier markets generally are subject to a greater risk of loss than investments in developed markets or emerging markets. Frontier market countries may have unstable governments that could have substantial influence over many aspects of the private sector, including by restricting foreign investment. Many frontier market countries may be dependent upon commodities, global trade or foreign aid and, accordingly, have been and may continue to be adversely affected by trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist measures imposed or negotiated by the countries with which they trade. The economies of frontier countries may be based on only a few industries, may be highly vulnerable to changes in local or global trade conditions and may suffer from extreme debt burdens or volatile inflation rates. The actions of a relatively few major investors in these markets are more likely to result in significant changes in local prices and the value of investments there. The risk also exists that an emergency situation may arise in one or more frontier market countries as a result of which trading of securities may cease or may be substantially curtailed and prices for investments in such markets may not be readily available. Brokerage commissions, custodial services and other costs relating to investment in frontier market countries generally are more expensive than those relating to investment in more developed markets.

Derivatives. Generally, derivatives can be characterized as financial instruments whose performance is derived at least in part from the performance of an underlying reference instrument. Derivative instruments may be acquired in the United States or abroad consistent with the Fund’s investment strategy and may include the various types of exchange-traded and over-the-counter (“OTC”) instruments described herein and other instruments with substantially similar characteristics and risks. Fund obligations created pursuant to derivative instruments may give rise to leverage, which may subject the Fund to heightened risk of loss. The Fund may invest in a derivative transaction if it is permitted to own, invest in, or otherwise have economic exposure to the reference instrument. Depending on the type of derivative instrument and the Fund’s investment strategy, a reference instrument could be a security, instrument, index, currency, commodity, economic indicator or event (“reference instruments”). The Fund may engage in derivative transactions to see return, to hedge against fluctuations in securities prices, interest rates or currency exchange rates, or as a substitute for the purchase or sale of securities or currencies.

Calvert Emerging Markets Focused Growth Fund12Prospectus dated May 1, 2024

ability to terminate OTC derivative instruments may depend on the cooperation of the counterparties to such contracts. For thinly traded derivative instruments, the only source of price quotations may be the selling dealer or counterparty. In addition, certain provisions of the Code limit the use of derivative instruments. Derivatives permit the Fund to increase or decrease the level of risk, or change the character of the risk, to which its portfolio is exposed in much the same way as the Fund can increase or decrease the level of risk, or change the character of the risk, of its portfolio by making investments in specific securities. There can be no assurance that the use of derivative instruments will benefit the Fund.

The U.S. and non-U.S. derivatives markets have undergone substantial changes in recent years as a result of changes under the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) in the United States and regulatory changes in Europe, Asia and other non-U.S. jurisdictions. In particular, the Dodd-Frank Act and related regulations require most derivatives to be margined and/or cleared and traded on an exchange, expand entity registration requirements, impose business conduct requirements on counterparties, and impose other regulatory requirements that impact derivatives markets. The SEC adopted Rule 18f-4 under the 1940 Act, which applies to the Fund’s use of derivative investments and certain financing transactions. Among other things, Rule 18f-4 requires certain funds that invest in derivative instruments beyond a specified limited amount (generally greater than 10% of a fund's net assets) to apply a value-at-risk based limit to their use of certain derivative instruments and financing transactions and to adopt and implement a derivatives risk management program. To the extent a Fund uses derivative instruments (excluding certain currency and interest rate hedging transactions) in a limited amount (up to 10% of a Fund's net assets), it will not be subject to the full requirements of Rule 18f-4. In addition, to the extent that the Fund enters into reverse repurchase agreements or similar financing transactions, the Fund may elect to either treat all of its reverse repurchase agreements or similar financing transactions as derivatives transactions for purposes of Rule 18f-4 or comply (with respect to reverse repurchase agreements or similar financing transactions) with the asset segregation requirements under Section 18 of the 1940 Act. The implementation of these requirements or additional future regulation of the derivatives markets may make the use of derivatives more costly, may limit the availability or reduce the liquidity of derivatives, and may impose limits or restrictions on the counterparties with which the Fund engages in derivative transactions. Fund management cannot fully predict the effects of any governmental regulation of the derivatives markets, and there can be no assurance that any government regulation will not adversely affect the Fund’s performance or ability to achieve its investment objective(s). Regulations adopted by federal banking regulators under the Dodd-Frank Act require that certain qualified financial contracts (“QFCs”) with counterparties that are part of U.S. or foreign global systemically important banking organizations be amended to include contractual restrictions on close-out and cross-default rights. QFCs include, but are not limited to, securities contracts, commodities contracts, forward contracts, repurchase agreements, securities lending agreements and swaps agreements, as well as related master agreements, security agreements, credit enhancements, and reimbursement obligations. If a covered counterparty of a Fund or certain of the covered counterparty’s affiliates were to become subject to certain insolvency proceedings, a Fund may be temporarily unable to exercise certain default rights, and the QFC may be transferred to another entity. In addition, under the rule, a Fund is permitted to invest in a security on a when-issued or forward-settling basis, or with a non-standard settlement cycle, and the transaction will be deemed not to involve a senior security under the 1940 Act, provided that (i) the Fund intends to physically settle the transaction and (ii) the transaction will settle within 35 days of its trade date (the “Delayed-Settlement Securities Provision”). A Fund may otherwise engage in such transactions that do not meet the conditions of the Delayed-Settlement Securities Provision so long as the Fund treats any such transaction as a “derivatives transaction” for purposes of compliance with the rule. Furthermore, under the rule, a Fund will be permitted to enter into an unfunded commitment agreement, and such unfunded commitment agreement will not be subject to the asset coverage requirements under the 1940 Act, if the Fund reasonably believes, at the time it enters into such agreement, that it will have sufficient cash and cash equivalents to meet its obligations with respect to all such agreements as they come due. These requirements may impact a Fund’s credit and counterparty risks.

Options. Options may be traded on an exchange and OTC. By buying a put option on a particular instrument, the Fund acquires a right to sell the underlying instrument at the exercise price. By buying a put option on an index, the Fund acquires a right to receive the cash difference between the strike price of the option and the index price at expiration. A purchased put position also typically can be sold at any time by selling at prevailing market prices. Purchased put options generally are expected to limit the Fund's risk of loss through a decline in the market value of the underlying security or index until the put option expires. When buying a put option, the Fund pays a premium to the seller of the option. If the price of the underlying security or index is above the exercise price of the option as of the option valuation date, the option expires worthless and the Fund will not be able to recover the option premium paid to the seller.

Calvert Emerging Markets Focused Growth Fund13Prospectus dated May 1, 2024

below the exercise price as of the option valuation date. If the value of the underlying security or index on the option’s expiration date is above the exercise price, the option will generally expire worthless and the Fund, as option seller, will have no obligation to the option holder.

The Fund may purchase call options. By purchasing a call option on a security, the Fund has the right to buy the security at the option’s exercise price. By buying a call option on an index, the Fund acquires the right to receive the cash difference between the market price of the index and strike price at expiration. Call options typically can be exercised any time prior to option maturity or, sold at the prevailing market price.

The Fund’s options positions are marked to market daily. The value of options is affected by changes in the value and dividend rates of their underlying instruments, changes in interest rates, changes in the actual or perceived volatility of the relevant index or market and the remaining time to the options’ expiration, as well as trading conditions in the options market. The hours of trading for options may not conform to the hours during which the underlying instruments are traded. To the extent that the options markets close before markets for the underlying instruments, significant price and rate movements can take place in the markets that would not be reflected concurrently in the options markets.

The Fund's ability to sell the instrument underlying a call option may be limited while the option is in effect unless the Fund enters into a closing purchase transaction. As the seller of a covered call option or an index call option, the Fund may forego, during the option’s life, the opportunity to profit from increases in the market value of the underlying instrument covering the call option above the sum of the premium received by the Fund and the exercise price of the call. The Fund also retains the risk of loss, minus the option premium received, should the price of the underlying instrument decline.

Participants in OTC markets are typically not subject to the same credit evaluation and regulatory oversight as are members of “exchange-based” markets. OTC option contracts generally carry greater liquidity risk than exchange-traded contracts. This risk may be increased in times of financial stress, if the trading market for OTC options becomes restricted. The ability of the Fund to transact business with any one or a number of counterparties may increase the potential for losses to the Fund, due to the lack of any independent evaluation of the counterparties or their financial capabilities, and the absence of a regulated market to facilitate settlement of the options.

Equity Swaps. Equity swaps involve the exchange by the Fund with another party of their respective returns as calculated on a notional amount of an equity index (such as the S&P 500® Index), basket of equity securities, or individual equity security.

Contracts for Difference. The Fund may purchase contracts for difference (“CFDs”). A CFD is a privately negotiated contract between two parties, buyer and seller, stipulating that the seller will pay to or receive from the buyer the difference between the nominal value of the underlying instrument at the opening of the contract and that instrument’s value at the end of the contract. The underlying instrument may be a single security, stock basket or index. A CFD can be set up to take either a short or long position on the underlying instrument. The buyer and seller are typically both required to post margin, which is adjusted daily. The buyer will also pay to the seller a financing rate on the notional amount of the capital employed by the seller less the margin deposit. A CFD is usually terminated at the buyer’s initiative. The seller of the CFD will simply match the exposure of the underlying instrument in the open market and the parties will exchange whatever payment is due.

Calvert Emerging Markets Focused Growth Fund14Prospectus dated May 1, 2024

As is the case with owning any financial instrument, there is the risk of loss associated with buying a CFD. For example, if a Fund buys a long CFD and the underlying security is worth less at the end of the contract, the Fund would be required to make a payment to the seller and would suffer a loss. Also, there may be liquidity risk if the underlying instrument is illiquid because the liquidity of a CFD is based on the liquidity of the underlying instrument. A further risk is that adverse movements in the underlying security will require the buyer to post additional margin. CFDs also carry counterparty risk, i.e., the risk that the counterparty to the CFD transaction may be unable or unwilling to make payments or to otherwise honor its financial obligations under the terms of the contract. If the counterparty were to do so, the value of the contract, and of the Fund’s shares, may be reduced. The Fund will not enter into a CFD transaction that is inconsistent with its investment objective, policies and strategies.

Structured Investments. The Fund may invest in structured investments. A structured investment is a derivative security designed to offer a return linked to a particular underlying security, currency, commodity or market, for which the amount of principal repayment and/or interest payments is based on the change in value of such underlying security, currency, commodity or market, including, among others, currency exchange rates, interest rates, referenced bonds and stock indices or other financial references. Structured investments may come in various forms, including notes, warrants and options to purchase securities, and may be listed and traded on an exchange or otherwise traded in the OTC market.

The Fund will typically use structured investments to gain exposure to a permitted underlying security, currency, commodity or market when direct access to such security, currency, commodity or market is limited or inefficient from a tax, cost or regulatory standpoint. Investments in structured investments involve risks including issuer risk, counterparty risk and market risk. Holders of structured investments bear risks of the underlying investment and are subject to issuer or counterparty risk because the holders are relying on the creditworthiness of such issuer or counterparty and have no rights with respect to the underlying investment. Certain structured investments may be thinly traded or have a limited trading market and may have the effect of increasing the Fund’s illiquidity to the extent that the Fund, at a particular point in time, may be unable to find qualified buyers for these investments.

A structured investment may be linked either positively or negatively to an underlying security, currency, commodity, index or market and a change in interest rates, principal amount, volatility, currency values or other factors, depending on the structured investment’s design, may result in a gain or loss that is a multiple of the movement of such interest rates, principal amount, volatility, currency values or other factors. Application of a multiplier is comparable to the use of financial leverage, a speculative technique. Leverage magnifies the potential for gain and the risk of loss. As a result, a relatively small decline in the value of the referenced factor could result in a relatively large loss in the value of a structured investment.

Other types of structured investments include interests in entities organized and operated for the purpose of restructuring the investment characteristics of underlying investment interests or securities. This type of securitization or restructuring usually involves the deposit or purchase of an underlying security by a U.S. or foreign entity, such as a corporation or trust of specified instruments, and the issuance by that entity of one or more classes of securities backed by, or representing an interest in, the underlying instruments. The cash flow or rate of return on the underlying investments may be apportioned among the newly issued securities to create different investment characteristics, such as varying maturities, credit quality, payment priorities and interest rate provisions. Structured investments that are subordinated, for example, in payment priority often offer higher returns, but may result in increased risks compared to other investments.

Forward Foreign Currency Exchange Contracts. A forward foreign currency exchange contract (“currency forward”) involves an obligation to purchase or sell a specific currency at a future date, which may be any fixed number of days from the date of the contract agreed upon by the parties, at a price set at the time of the contract. These contracts may be bought or sold to protect against an adverse change in the relationship between currencies or to increase exposure to a particular foreign currency.

Certain currency forwards may be individually negotiated and privately traded, exposing them to credit and counterparty risks. The precise matching of the currency forward amounts and the value of the instruments denominated in the corresponding currencies will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that the use of currency forwards may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that currency forwards may create exposure to currencies in which the Fund’s securities are not denominated. In addition, it may not be possible to hedge against long-term currency changes. Currency forwards are subject to the risk of political and economic factors applicable to the countries issuing the underlying currencies. Furthermore, unlike trading in most other types of instruments, there is no systematic reporting of last sale information with respect to the foreign currencies underlying currency forwards. As a result, available information may not be complete.

Calvert Emerging Markets Focused Growth Fund15Prospectus dated May 1, 2024

Counterparty Risk. A financial institution or other counterparty with whom the Fund does business (such as trading, securities lending or as a derivatives counterparty), or that underwrites, distributes or guarantees any instruments that the Fund owns or is otherwise exposed to, may decline in financial condition and become unable to honor its commitments. This could cause the value of Fund shares to decline or could delay the return or delivery of collateral or other assets to the Fund. Counterparty risk is increased for contracts with longer maturities.

Fixed-Income Securities and Other Debt Instruments. Fixed-income securities and other debt instruments include all types of fixed and floating-rate bonds and notes, such as convertible securities and other hybrid securities (other than preferred stock); corporate commercial paper; mortgage-backed and other asset-backed securities; inflation-indexed bonds issued by both governments and corporations; structured notes, including “indexed” securities; loans; loan participations and assignments; delayed funding loans and revolving credit facilities; and bank certificates of deposit, fixed time deposits, bank deposits (or investments structured to provide the same type of exposure) and bankers’ acceptances of foreign and domestic banks and other debt instruments. Fixed-income securities and other debt instruments are issued by: foreign governments or their subdivisions, agencies and government-sponsored enterprises; sovereign entities; international agencies or supranational entities; the U.S. Government, its agencies or government-sponsored enterprises (or guaranteed thereby); central or quasi-sovereign banks and U.S. and foreign corporations. Fixed-income securities and other debt instruments include deep discount bonds, such as zero coupon bonds, deferred interest bonds, bonds or securities on which the interest is payable in-kind (“PIK securities”), which are debt obligations that are issued at a significant discount from face value, and securities purchased on a forward commitment or when-issued basis. While zero coupon bonds do not make periodic payments of interest, deferred interest bonds provide for a period of delay before the regular payment of interest begins. PIK securities provide that the issuer thereof may, at its option, pay interest in cash or in the form of additional securities. The market price of a fixed-income investment can decline due to market-related factors, including rising interest rates and widening credit spreads, rising inflation, or decreased liquidity due to, for example, market uncertainty about the value of a fixed-income investment (or class of fixed income investments).

Exchange-Traded Funds (“ETFs”). The Fund may invest in ETFs. ETFs are subject to the risks of investing in the underlying securities or other instruments that they own. The market for common shares of ETFs, which are generally traded on an exchange and may be traded at a premium or discount to net asset value, is affected by the demand for those securities, regardless of the value of such ETF’s underlying securities. Additionally, natural or environmental disasters, widespread disease or other public health issues, war, acts of terrorism or other events could result in increased premiums or discounts to an ETF’s net asset value. The Fund will indirectly bear its proportionate share of any management fees and other operating expenses paid by ETFs in which it invests. If such fees exceed 0.01%, the costs associated with such investments will be reflected under Acquired Fund Fees and Expenses in the Fund’s Annual Fund Operating Expenses table(s) in its Fund Summary. Requirements of the federal securities laws may limit the Fund’s ability to invest in other investment companies, including ETFs. Investments in a pooled investment vehicle will be included in satisfying the Fund’s 80% Policy if the vehicle invests at least 80% of its net assets in the types of investments included in the Fund’s 80% Policy.

Issuer Non-Diversification. The Fund is a “non-diversified” fund can invest more of its assets in a smaller number of issuers than diversified funds. Focusing investments in a smaller number of issuers could result in greater potential losses than for funds investing in a broader variety of issuers, and the value of a non-diversified fund's shares may be more volatile than the values of shares of more diversified funds. However, the Fund intends to qualify as a regulated investment company under the Code. This requires the Fund to limit its investments so that, at the end of each fiscal quarter, at least 50% of the Fund’s total assets are invested in (i) cash and cash items, U.S. Government securities and securities of other regulated investment companies, and (ii) single issuers that are less than 5% of the total assets of the

Calvert Emerging Markets Focused Growth Fund16Prospectus dated May 1, 2024

Fund and not more than 10% of the outstanding voting shares of the issuer. In addition, at the end of each fiscal quarter, not more than 25% of the value of the Fund’s total assets can be invested, including through corporations in which the Fund owns a 20% or more voting stock interest, in the securities (other than those of the U.S. Government or other regulated investment companies) of any one issuer or of two or more issuers that the Fund controls and that are engaged in the same, similar, or related trades or businesses.

Restricted Securities. Securities held by the Fund may be legally restricted as to resale (such as those issued in private placements), including commercial paper issued pursuant to Section 4(a)(2) of the 1933 Act, securities eligible for resale pursuant to Rule 144A thereunder, and securities of U.S. and non-U.S. issuers initially offered and sold outside the United States pursuant to Regulation S thereunder. Restricted securities may not be listed on an exchange and may have no active trading market. The Fund may incur additional expense when disposing of restricted securities, including all or a portion of the cost to register the securities. The Fund also may acquire securities through private placements under which it may agree to contractual restrictions on the resale of such securities that are in addition to applicable legal restrictions. In addition, if the investment adviser and/or sub-adviser, if applicable, receives non-public information about the issuer, the Fund may as a result be unable to sell the securities.

Convertible Securities. A convertible security is a bond, debenture, note, preferred security, or other security that entitles the holder to acquire common stock or other equity securities of the same or a different issuer. A convertible security entitles the holder to receive interest paid or accrued or dividends paid until the convertible security matures or is redeemed, converted or exchanged. Before conversion, convertible securities have characteristics similar to nonconvertible income securities.

Holders of convertible securities generally have a claim on the assets of the issuer prior to the common stockholders but may be subordinated to other debt securities of the same issuer. Certain convertible debt securities may provide a put option to the holder, which entitles the holder to cause the securities to be redeemed by the issuer at a premium over the stated principal amount of the debt securities under certain circumstances. Certain convertible securities may include loss absorption characteristics that make the securities more debt-like. This is particularly true of convertible securities issued by companies in the financial services sector.

The value of a convertible security may be influenced by changes in interest rates, with investment value declining as interest rates increase and increasing as interest rates decline. The credit standing of the issuer and other factors also may have an effect on the convertible security’s investment value. A convertible security may be subject to redemption at the option of the issuer at a price established in the convertible security’s governing instrument.

Hybrid Securities. Hybrid securities generally possess certain characteristics of both equity and debt securities. These securities may at times behave more like equity than debt, or vice versa. Preferred stocks, convertible securities, trust preferred securities and certain debt obligations are types of hybrid securities. The investment adviser has sole discretion to determine whether an investment has hybrid characteristics and generally will consider the instrument’s preference over the issuer’s common shares, the term of the instrument at the time of issuance, and/or the tax character of the instrument’s distributions. Hybrid securities generally do not have voting rights or have limited voting rights. Hybrid securities may be subject to redemption at the option of the issuer at a predetermined price. Hybrid securities may pay a fixed or variable rate of interest or dividends. The prices and yields of nonconvertible hybrid securities generally move with changes in interest rates and the issuer’s credit quality, similar to the factors affecting debt securities. If the issuer of a hybrid security experiences financial difficulties, the value of such security may be adversely affected similar to the issuer’s outstanding common stock or subordinated debt instruments.

Because hybrid securities have both debt and equity characteristics, their values vary in response to many factors, including issuer-specific events, credit spreads and, for convertible securities, factors affecting the securities into which they convert. Trust preferred securities are issued by a special purpose trust that holds the subordinated debt of a company and, as such, are subject to the risks associated with such debt obligation.

Calvert Emerging Markets Focused Growth Fund17Prospectus dated May 1, 2024

not have voting rights or have limited voting rights and have economic characteristics similar to fixed-income securities. Preferred stocks generally are issued with a fixed par value and pay dividends based on a percentage of that par value at a fixed or variable rate. Dividend payments on preferred stocks may be subordinate to interest payments on the issuer’s debt obligations. Certain preferred stocks may be convertible to common stock. Additionally, preferred stocks often have a liquidation value that generally equals the original purchase price of the preferred stock at the date of issuance.

Preferred stocks are subject to issuer-specific and market risks generally applicable to equity securities and credit and interest rate risks generally applicable to fixed-income securities. The value of preferred stock may react more strongly than bonds and other debt instruments to actual or perceived changes in the company’s financial condition or prospects. Preferred stocks are considered an equity security.

Information Technology Sector Risk. If the Fund concentrates investments in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, competition for the services of qualified personnel and government regulation. The products of information technology companies may face product obsolescence due to rapid technological developments and frequent new product introduction and unpredictable changes in growth rates. Companies in the information technology sector also can be heavily dependent on patent protection and the expiration of patents may adversely affect the profitability of these companies. As a result, the value of shares may fluctuate more than that of a fund that does not concentrate in companies in the technology sector.

Consumer Discretionary Sector Risk. To the extent the Fund invests a substantial portion of its assets in the consumer discretionary sector, the value of Fund shares may be particularly impacted by events that adversely affect the consumer discretionary sector. The consumer discretionary sector, which encompasses companies that sell nonessential goods and services to consumers, is sensitive to macroeconomic conditions. The success of consumer product manufacturers and retailers is tied closely to the performance of domestic and international economies, interest rates, inflationary pressures, currency exchange rates, supply chains, competition, consumer confidence, changes in demographics and consumer preferences. Companies in the consumer discretionary sector depend heavily on disposable household income and consumer spending, and may be strongly affected by social trends and marketing campaigns and other economic or social factors affecting consumer demand. These companies may be subject to competition, which may have an adverse impact on their profitability. Governmental regulation, including price controls and regulations on packaging, labeling, competition, and certification, may affect the profitability of certain companies in which the Fund may invest. Companies operating in this sector may also be adversely affected by government and private litigation.

Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Companies in the financials sector may be subject to extensive government regulations that affect the scope of their activities, the prices they can charge for products and services, and the amount of capital they must maintain. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector. Global economies and financial markets are becoming increasingly interconnected, which increases the possibility that conditions in one country or region may adversely affect issuers in another country or region, which may adversely affect securities held by the Fund. In addition, adverse developments that affect financial institutions or the financials sector generally, or concerns or rumors about any events of these kinds or other similar risks, may reduce liquidity in the market generally or have other adverse effects on the economy, the Fund, or issuers in which the Fund invests. The Fund and issuers in which it invests may not be able to identify all potential solvency or stress concerns with respect to a financial institution or to transfer assets from one bank or financial institution to another in a timely manner in the event such bank or financial institution comes under stress or fails.

Geographic Risk. Because the Fund may invest significantly in a particular geographic region, country, or group of countries, the value of Fund shares may be affected by the economic, political, social, or other conditions that affect that region, country, or group of countries. The Fund’s NAV may be more volatile than that of a fund that invests more broadly.

Calvert Emerging Markets Focused Growth Fund18Prospectus dated May 1, 2024

and maintained in an amount at least equal to the market value of the securities loaned. The Fund may engage in securities lending to generate income. Upon return of the loaned securities, the Fund would be required to return the related collateral to the borrower and may be required to liquidate portfolio securities in order to do so. The Fund may lend up to one-third of the value of its total assets or such other amount as may be permitted by law.

Cash and Money Market Instruments; Temporary Defensive Positions. The Fund may invest in cash or money market instruments, including high quality short-term instruments or an affiliated investment company that invests in such instruments. During unusual market conditions, including for temporary defensive purposes, the Fund may invest up to 100% of its assets in cash or money market instruments, which may be inconsistent with its investment objective(s) and other policies, and as such, the Fund may not achieve its investment objective(s) during this period.

Converting to Hub and Spoke Structure. The Fund may invest all of its assets in an open-end management investment company (“Portfolio”) with substantially the same investment objective, policies and restrictions as the Fund. Any such Portfolio would be advised by the Fund’s investment adviser (or an affiliate) and the Fund would not pay directly any advisory fee with respect to the assets so invested. The Fund may initiate investments in a Portfolio at any time without shareholder approval.

Calvert Emerging Markets Focused Growth Fund19Prospectus dated May 1, 2024

securities or the entire market, which could prevent the Fund from, among other things, buying or selling the Fund or accurately pricing its securities. Like other funds and business enterprises, the Fund and its service providers have experienced, and will continue to experience, cyber incidents consistently. In addition to deliberate cyber attacks, unintentional cyber incidents can occur, such as the inadvertent release of confidential information by the Fund or its service providers.

The Fund uses third party service providers who are also heavily dependent on computers and technology for their operations. Cybersecurity failures by or breaches of the Fund’s investment adviser or administrator and other service providers (including, but not limited to, the custodian or transfer agent), and the issuers of securities in which the Fund invests, may disrupt and otherwise adversely affect their business operations. This may result in financial losses to the Fund, impede Fund trading, interfere with the Fund’s ability to calculate its NAV, limit a shareholder’s ability to purchase or redeem shares of the Fund or cause violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, litigation costs, or additional compliance costs. While many of the Fund’s service providers have established business continuity plans and risk management systems intended to identify and mitigate cyber attacks, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified. The Fund cannot control the cybersecurity plans and systems put in place by service providers to the Fund and issuers in which the Fund invests. The Fund and its shareholders could be negatively impacted as a result.

General. Unless otherwise stated, the Fund's investment objective and certain other policies may be changed without shareholder approval. Shareholders will receive 60 days' advance written notice of any material change in the investment objective. The Fund might not use all of the strategies and techniques or invest in all of the types of securities described in this Prospectus or the SAI. While at times the Fund may use alternative investment strategies in an effort to limit its losses, it may choose not to do so.

Calvert Emerging Markets Focused Growth Fund20Prospectus dated May 1, 2024

The Fund’s annual operating expenses are expressed as a percentage of the Fund’s average daily net assets and may change as Fund assets increase and decrease over time. Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective. In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. Mutual funds, investment advisers, other market participants and many securities markets are subject to rules and regulations and the jurisdiction of one or more regulators. Changes to applicable rules and regulations or to widely accepted market conventions or standards could have an adverse effect on securities markets and market participants, as well as on the Fund’s ability to execute its investment strategy. With the increased use of technologies by Fund service providers, such as the Internet, to conduct business, the Fund is susceptible to operational, information security and related risks. See “Additional Information about Investment Strategies and Risks” in the Fund’s SAI. In addition, it is expected that confidential or material non-public information regarding an investment or potential investment opportunity may become available to the investment adviser. If such information becomes available, the investment adviser may be precluded (including by applicable law or internal policies or procedures) from pursuing an investment or disposition opportunity with respect to such investment or investment opportunity and the investment adviser may be restricted in its ability to cause the Fund to buy or sell securities of an issuer for substantial periods of time when the Fund otherwise could realize profit or avoid loss. This may adversely affect the Fund's flexibility with respect to buying or selling securities and may impair the Fund's liquidity.

About Responsible Investing

Investment Selection Process

CRM seeks to invest in issuers that manage ESG risk exposures adequately and that are not exposed to excessive ESG risk through their principal business activities. Issuers are analyzed using The Calvert Principles for Responsible Investment (the “Calvert Principles”) (included as Appendix A to this Prospectus), a framework for considering ESG factors. Each issuer is evaluated relative to an appropriate peer group based on financially material ESG factors as determined by CRM. CRM’s evaluation of a particular security’s responsible investing characteristics generally involves both quantitative and qualitative analysis. In assessing investments, CRM generally focuses on the ESG factors relevant to the issuer’s operations, and an issuer may be acceptable for investment based primarily on such assessment. Securities may be deemed suitable for investment even if the issuer does not operate in accordance with all elements of the Fund’s responsible investing criteria. The Fund may also invest in issuers that CRM believes are likely to operate in accordance with the Calvert Principles pending CRM’s engagement activity with such issuer. In assessing issuers for which quantitative data is limited, subjective judgments may serve as the primary basis for CRM’s evaluation. The responsible investing criteria of the Fund may be changed by the Board without shareholder approval.

Calvert Emerging Markets Focused Growth Fund21Prospectus dated May 1, 2024

education, health, and sustainable agriculture (collectively, the “Participating Borrowers”) with missions that may include addressing climate change, supporting quality education, promoting financial inclusion, strengthening women’s empowerment, and increasing access to quality affordable housing. CIC issues Notes with fixed interest rates determined at the time of issuance and terms currently ranging from six months to 20 years, and in turn makes loans to Participating Borrowers at rates determined through consideration of the general current market, the Participating Borrower’s positive social and/or environmental impact and the Participating Borrower’s risk level.

The Adviser has licensed use of the Calvert name to CIC and provides other types of support. An officer of the Adviser serves on the CIC Board.

Shareholder Advocacy and Corporate Responsibility

CRM uses strategic engagement and shareholder advocacy to encourage positive change in companies. CRM's activities may include, but are not limited to:

Direct Dialogue with Company Management. CRM, or its agent, may initiate dialogue with management through phone calls, letters and in-person meetings. Through its interaction, CRM seeks to learn about management’s successes and challenges and to press for improvement on issues of concern.

Proxy Voting. As a shareholder of the companies in its portfolio, the Fund typically has an opportunity each year to express its views on issues of corporate governance and sustainability at annual stockholder meetings. CRM votes proxies consistent with CRM’s Proxy Voting Policies and Procedures attached to the SAI.

Shareholder Resolutions. CRM may propose that companies submit resolutions to their shareholders on a variety of ESG issues. CRM believes that submitting shareholder resolutions may help establish dialogue with management and encourage companies to take action.

Management and Organization

Pursuant to an investment sub-advisory agreement, CRM has delegated the investment management of the Fund to Morgan Stanley Investment Management Company (“MSIM Company”), a registered investment adviser. MSIM Company is located at 23 Church Street, 16-01 Capital Square, Singapore 049481. CRM pays MSIM Company a portion of the advisory fee for sub-advisory services provided to the Fund. MSIM Company is a wholly owned subsidiary of Morgan Stanley.

Under its investment advisory agreement, CRM receives a monthly advisory fee equal to 0.75% annually of the Fund’s average daily net assets. For the period May 31, 2023 (commencement of operations) to December 31, 2023, the effective annual rate of advisory fee paid was 0.75% of average daily net assets.

The portfolio manager of the Fund is Vishal Gupta (since inception). Mr. Gupta is a Managing Director of MSIM Company and has been associated with Morgan Stanley Investment Management Inc. in an investment management capacity since 2014. He currently manages other funds.

The Statement of Additional Information provides additional information about the portfolio manager’s compensation, other accounts managed by the portfolio manager, and the portfolio manager’s ownership of Fund shares.

CRM serves as administrator of the Fund, providing the Fund with administrative services and related office facilities. In return, each Class of the Fund is authorized to pay CRM a monthly administrative fee equal to 0.12% annually of average daily net assets. For the period May 31, 2023 (commencement of operations) to December 31, 2023, the administrative fees paid by the Fund (as a percentage of average daily net assets) were 0.12% for each share class.

Calvert Emerging Markets Focused Growth Fund22Prospectus dated May 1, 2024

Valuing Shares

Pursuant to the Procedures, if market quotations are not readily available (or otherwise not reliable) for a particular investment, the fair value of the investment will be determined by the investment adviser, as valuation designee. A market quotation is readily available only when that quotation is a quoted price (unadjusted) in active markets for identical investments that the Fund can access at the measurement date, provided that a quotation will not be readily available if it is not reliable. As such, the Fund will use fair value pricing if, for example, market prices or a pricing service's prices (as applicable) are unavailable or deemed unreliable, or if events occur after the close of a securities market (usually a foreign market) and before portfolio assets are valued that cause or are likely to cause a market quotation to be unavailable or unreliable, such as corporate actions, regulatory news, or natural disasters or governmental actions that may affect investments in a particular sector, country or region. In addition, for foreign equity securities and total return swaps and futures contracts on foreign indices that meet certain criteria, the Board has approved the use of a fair value service that values such investments to reflect market trading that occurs after the close of the applicable foreign markets of comparable securities or other investments that have a strong correlation to the fair valued investments. An investment that is fair valued may be valued at a price higher or lower than (i) actual market quotations, (ii) the value determined by other funds using their own fair valuation procedures, or (iii) the price at which the investment could have been sold during

Calvert Emerging Markets Focused Growth Fund23Prospectus dated May 1, 2024

the period in which fair valuation was used with respect to such investment to calculate the Fund’s NAV. Because foreign investments held by the Fund, if any, may trade on days when Fund shares are not priced, the value of such investments, and thus the net asset value of the Fund’s shares, can change on days when Fund shares cannot be redeemed or purchased. CRM has established a Valuation Committee that oversees the valuation of investments.

Purchasing Shares

Class A and Class C Shares

Your initial investment must be at least $1,000. After your initial investment, additional investments may be made in any amount at any time by sending a check payable to the order of the Fund or the transfer agent directly to the transfer agent (see back cover for address). Please include your name and account number and the name of the Fund and Class of shares with each investment. The Fund does not accept direct purchases of Class C shares by accounts for which no broker-dealer or other financial intermediary is specified. Any direct purchase received by the Fund's transfer agent for Class C shares for such accounts will automatically be invested in Class A shares.

The minimum initial investment amount and Fund policy of redeeming accounts with low account balances are waived for bank automated investing accounts, certain group purchase plans (including employer sponsored retirement plans and proprietary fee-based programs sponsored by financial intermediaries) and for persons affiliated with CRM, its affiliates and certain Fund service providers (as described in the SAI).

Class I Shares

Calvert Emerging Markets Focused Growth Fund24Prospectus dated May 1, 2024

Class R6 Shares

Class R6 shares are offered to employer sponsored retirement plans held in plan level or omnibus accounts; endowments; foundations; local, city, and state governmental institutions; corporations; charitable trusts; trust companies; private banks and their affiliates; and insurance companies; investors who purchase shares through asset-based fee programs of certain financial intermediaries that have entered into an agreement with the Fund’s principal underwriter to offer Class R6 shares through such programs; and investment companies. In order to offer Class R6 shares to investors other than employer sponsored retirement plans, a financial intermediary must enter into a written agreement with the Fund’s principal underwriter to offer such shares.

There is no initial investment minimum for: employer sponsored retirement plans; private banks and their affiliates; investors who purchase shares through asset-based fee programs as described above, provided the aggregate value of such program’s assets under management invested in Calvert funds is at least $5,000,000; and investment companies sponsored by the Calvert organization. For all other eligible investors, the initial investment must be at least $5,000,000. Subsequent investments of any amount may be made at any time. Please call 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time) for further information.

Class R6 shares may be purchased through a financial intermediary or by requesting your bank to transmit immediately available funds (Federal Funds) by wire. To make an initial investment by wire, you must complete an account application and telephone Calvert Shareholder Services at 1-800-368-2745 to be assigned an account number. You may request an account application by calling 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time). Shareholder Services must be advised by telephone of each additional investment by wire.

Inactive Accounts and Risk of Escheatment. In accordance with state “unclaimed property” laws, your Fund shares may legally be considered abandoned and required to be transferred to the relevant state (also known as “escheatment”) under various circumstances. These circumstances, which vary by state, can include inactivity (e.g., no owner-initiated contact for a certain period), returned mail (e.g., when mail sent to a shareholder is returned by the post office as undeliverable), uncashed checks or a combination of these. An incorrect address may cause a shareholder’s account statements and other mailings to be returned to the Fund or your financial intermediary. Since states’ statutory requirements regarding inactivity differ, it is important to regularly contact your financial intermediary or the Fund’s transfer agent. The process described above, and the application of state escheatment laws, may vary by state and/or depending on how shareholders hold their shares in the Fund.

Calvert Emerging Markets Focused Growth Fund25Prospectus dated May 1, 2024

For more information, please see https://www.calvert.com/mutual-funds-and-abandoned-property.php or please contact us at 1-800-368-2745.

A fund that invests all or a portion of its assets in foreign securities may be susceptible to a time zone arbitrage strategy in which shareholders attempt to take advantage of fund share prices that may not reflect developments in a foreign securities market that occur after the close of such market but prior to the pricing of fund shares. In addition, a fund that invests in securities that are, among other things, thinly traded, traded infrequently or illiquid, is susceptible to the risk that the current market price for such securities may not accurately reflect current market values. A shareholder may seek to engage in short-term trading to take advantage of these pricing differences (commonly referred to as “price arbitrage”). The investment adviser(s) and sub-adviser(s) are authorized to use the fair value of a security if prices are unavailable or are deemed unreliable (see “Valuing Shares”). The use of fair value pricing and the restrictions on excessive trading and market timing described below are intended to reduce a shareholder’s ability to engage in price or time zone arbitrage to the detriment of the Fund.

Pursuant to the Policy, “two round-trips” completed by a Fund shareholder within 90 days through one or more accounts (the “Limitation”) generally will be deemed to be indicative of market timing or trading excessively in fund shares. A “round trip” is defined as a purchase or exchange into a Fund followed or preceded by a redemption or exchange out of the Fund. Purchases and redemptions subject to the Limitation include those made by exchanging to or from another fund. Eaton Vance will evaluate transactions in Fund shares that violate the Limitation to determine whether they are likely to be detrimental to the Fund. In making such a determination, Eaton Vance may consider various factors, such as the amount, frequency and nature of trading activity. If such a determination is made, the Fund shareholder may be subject to restrictions on trading Fund shares, as described above. Eaton Vance uses reasonable efforts to detect market timing and excessive trading activity that is likely to be detrimental to the Fund, but it cannot ensure that it will be able to identify all such cases. Eaton Vance may also reject or cancel any purchase order (including an exchange) from a shareholder or group of shareholders for any other reason. In applying the Policy, and in particular when determining whether a transaction is likely to be detrimental to a Fund, Eaton Vance will be required to make judgments that are inherently subjective and will depend on the specific facts and circumstances. Such determinations will be made in a manner believed to be in the best interest of the Fund’s shareholders. No Calvert fund has any arrangement to permit market timing.

The following Fund share transactions generally are exempt from the Policy because they generally do not raise market timing or excessive trading concerns:

Calvert Emerging Markets Focused Growth Fund26Prospectus dated May 1, 2024

·transactions in shares of Calvert Ultra-Short Duration Income Fund; or

·transactions made by model-based discretionary advisory accounts; or

·transactions made by funds that invest in the Fund as part of an asset reallocation in accordance with their investment policies or in response to Fund inflows and outflows.

·how long you expect to own your shares;

·how much you intend to invest; and

·the total operating expenses associated with owning each class.

Class A shares are offered at net asset value plus a front-end sales charge of up to 5.25%. This charge is deducted from the amount you invest. The Class A sales charge is reduced for purchases of $50,000 or more. The sales charge applicable to your purchase may be reduced under the right of accumulation or a statement of intention, which are described in “Reducing or Eliminating Class A Sales Charges” under “Sales Charges” below. Some investors may be eligible to purchase Class A shares at net asset value under certain circumstances, which are also described below. Class A shares pay distribution and service fees equal to 0.25% annually of average daily net assets.

Class C shares are offered through financial intermediaries at net asset value with no front-end sales charge. If you sell your Class C shares within 12 months of purchase, you generally will be subject to a contingent deferred sales charge or “CDSC.” The CDSC is deducted from your redemption proceeds. Under certain circumstances, the CDSC for Class C may be waived (such as certain redemptions from employer sponsored retirement plans). See “CDSC Waivers” under “Sales Charges” below. Class C shares pay distribution and service fees equal to 1.00% annually of average daily net assets. Orders for Class C shares of one or more Calvert funds will be refused when the total value of the purchase (including the aggregate market value of all Calvert fund shares held within the purchasing shareholder’s account(s)) is $1 million or more. Investors considering cumulative purchases of $1 million or more should consider whether another Class of shares would be more appropriate and consult their financial intermediary. The Fund no longer accepts direct purchases of Class C shares by accounts for which no broker-dealer or other financial intermediary is specified. Any direct purchase received by the Fund’s transfer agent for Class C shares for such accounts will automatically be invested in Class A shares. In addition, Class C shares held in an account for which no financial intermediary is specified and which are not subject to a CDSC will periodically be converted to Class A shares.

Calvert Emerging Markets Focused Growth Fund27Prospectus dated May 1, 2024

underwriter to offer Class I shares solely when acting as an agent for the investor. An investor acquiring Class I shares through such platforms may be required to pay a commission and/or other forms of compensation to the broker. Class I shares are also offered to investment and institutional clients of CRM and its affiliates, and certain persons affiliated with CRM (including employees, officers and directors of CRM’s affiliates). Class I shares do not pay distribution or service fees.

Class R6 shares are offered at net asset value to employer sponsored retirement plans and certain other investors as described under “Class R6 Shares” above. Class R6 shares are not subject to distribution fees, service fees or sub-accounting/recordkeeping or similar fees paid to financial intermediaries.

Certain financial intermediaries that maintain fund accounts for the benefit of their customers provide sub-accounting, recordkeeping and/or administrative services to the Calvert funds and are compensated for such services by the funds, provided that no such compensation is paid with respect to Class R6 shares. As used in this Prospectus, the term “financial intermediary” includes any broker, dealer, bank (including bank trust departments), registered investment adviser, financial planner, a retirement plan and/or its administrator, their designated intermediaries and any other firm having a selling, administration or similar agreement with the principal underwriter or its affiliates.

Sales Charges

Amount of Purchase	Sales Charge* as a Percentage of Offering Price	Sales Charge* as a Percentage of Net Amount Invested	Dealer Commission as a Percentage of Offering Price
Less than $50,000	5.25%	5.54%	4.75%
$50,000 but less than $100,000	4.50%	4.71%	4.00%
$100,000 but less than $250,000	3.50%	3.63%	3.00%
$250,000 but less than $500,000	2.50%	2.56%	2.00%
$500,000 but less than $1,000,000	2.00%	2.04%	1.50%
$1,000,000 or more	0.00**	0.00**	TIERED**

**No sales charge is payable at the time of purchase on investments of $1 million or more. The principal underwriter will pay a commission to financial intermediaries on sales of $1 million or more as follows: 1.00% on amounts of $1 million or more but less than $4 million; plus 0.50% on amounts of $4 million but less than $15 million; plus 0.25% on amounts of $15 million or more. A CDSC of 1.00% will be imposed on such investments (as described below) in the event of redemptions within 12 months of purchase.

Calvert Emerging Markets Focused Growth Fund28Prospectus dated May 1, 2024

foregoing persons is the sole beneficiary (including employer sponsored retirement plans and IRAs) may be combined for purposes of the right of accumulation. Shares purchased and/or owned in a SEP, SARSEP and SIMPLE IRA plan may be combined for purposes of the right of accumulation for the plan and its participants. You may be required to provide documentation to establish your ownership of shares included under the right of accumulation (such as account statements for you, your spouse and children or marriage certificates, birth certificates and/or trust or other fiduciary-related documents).

Statement of Intention. Under a statement of intention, purchases of $50,000 or more made over a 13-month period are eligible for reduced sales charges. Shares eligible under the right of accumulation (other than those included in employer sponsored retirement plans) may be included to satisfy the amount to be purchased under a statement of intention. Under a statement of intention, the principal underwriter may hold 5% of the dollar amount to be purchased in escrow in the form of shares registered in your name until you satisfy the statement or the 13-month period expires. A statement of intention does not obligate you to purchase (or the Fund to sell) the full amount indicated in the statement. If during the 13-month period you redeem any of the shares that you purchased pursuant to the statement of intention, the value of the redeemed shares will not be included for purposes of satisfying your statement of intention. For additional information about statements of intention, see “Sales Charges” in the SAI.

Contingent Deferred Sales Charge. Class A and Class C shares are subject to a CDSC on certain redemptions. The CDSC generally is paid to the principal underwriter. Class A shares purchased at net asset value in amounts of $1 million or more are subject to a 1.00% CDSC if redeemed within 12 months of purchase. Class C shares are subject to a 1.00% CDSC if redeemed within 12 months of purchase. CDSCs are based on the lower of the net asset value at the time of purchase or at the time of redemption. Shares acquired through the reinvestment of distributions are exempt from the CDSC. Redemptions are made first from shares that are not subject to a CDSC.

The sales commission payable to financial intermediaries in connection with sales of Class C shares is described under “Distribution and Service Fees” below.

Calvert Emerging Markets Focused Growth Fund29Prospectus dated May 1, 2024

Calvert Emerging Markets Focused Growth Fund30Prospectus dated May 1, 2024

Redeeming Shares

You can redeem shares in any of the following ways:

By Mail	Send your request to the transfer agent (see back cover for address). The request must be signed exactly as your account is registered (for instance, a joint account must be signed by all registered owners to be accepted) and a Medallion signature guarantee may be required. Circumstances that may require a Medallion signature guarantee include, but are not limited to, requests to distribute redemption proceeds to a party other than the registered account owner(s); requests to mail redemption proceeds to an address other than the address of record; requests to distribute proceeds to a bank account not on file; requests to re-issue uncashed checks representing redemption proceeds; or transaction requests from an account beneficiary when an account owner is deceased. You can obtain a Medallion signature guarantee at banks, savings and loan institutions, credit unions, securities dealers, securities exchanges, clearing agencies and registered securities associations that participate in The Securities Transfer Agents Medallion Program, Inc. (STAMP, Inc.). Only Medallion signature guarantees issued in accordance with STAMP, Inc. will be accepted. You may be asked to provide additional documents if your shares are registered in the name of a corporation, partnership or fiduciary.
By Telephone	Certain shareholders can redeem by calling 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time). Proceeds of a telephone redemption are generally limited to $100,000 per account (which may include shares of one or more Calvert funds) and can be sent only to the account address or to a bank pursuant to prior instructions.
By Internet	Certain shareholders can redeem by logging on to the Calvert website at www.calvert.com. Proceeds of internet redemptions are generally limited to $100,000 per account (which may include shares of one or more Calvert funds) and can be sent only to the account address or to a bank pursuant to prior instructions.
For Additional Information	Please call 1-800-368-2745 Monday through Thursday, 9:00 a.m. to 5:30 p.m. (Eastern Time) and Friday, 9:00 a.m. to 5:00 p.m. (Eastern Time).
Through a Financial Intermediary	Your financial intermediary is responsible for transmitting the order promptly. A financial intermediary may charge a fee for this service.

Calvert Emerging Markets Focused Growth Fund31Prospectus dated May 1, 2024

Shareholder Account Features

Distributions. You may have your Fund distributions paid in one of the following ways:

• Full Reinvest Option	Distributions are reinvested in additional shares. This option will be assigned if you do not specify an option.
• Partial Reinvest Option	Dividends and short-term capital gains are paid in cash* and long-term capital gains are reinvested in additional shares.
• Cash Option	Distributions are paid in cash.*
• Exchange Option	Distributions are reinvested in additional shares of any class of another Calvert fund chosen by you, subject to the terms of that fund’s prospectus. Before selecting this option, you must obtain a prospectus of the other fund and consider its objectives, risks, and charges and expenses carefully.

Information about the Fund. From time to time, you may receive the following:

·Semiannual and annual reports containing a list of portfolio holdings as of the end of the second and fourth fiscal quarters, respectively, performance information and financial statements.

·Periodic account statements, showing recent activity and total share balance.

·Tax information needed to prepare your income tax returns.

·Proxy materials, in the event a shareholder vote is required.

·Special notices about significant events affecting your Fund.

Calvert Emerging Markets Focused Growth Fund32Prospectus dated May 1, 2024

Calvert Emerging Markets Focused Growth Fund33Prospectus dated May 1, 2024

Potential Conflicts of Interest

Calvert Emerging Markets Focused Growth Fund34Prospectus dated May 1, 2024

Material Non-Public Information. It is expected that confidential or material non-public information regarding an investment or potential investment opportunity may become available to the investment adviser. If such information becomes available, the investment adviser may be precluded (including by applicable law or internal policies or procedures) from pursuing an investment or disposition opportunity with respect to such investment or investment opportunity. Morgan Stanley has established certain information barriers and other policies to address the sharing of information between different businesses within Morgan Stanley. In limited circumstances, however, including for purposes of managing business and reputational risk, and subject to policies and procedures and any applicable regulations, Morgan Stanley personnel, including personnel of the investment adviser, on one side of an information barrier may have access to information and personnel on the other side of the information barrier through “wall crossings.” The investment adviser faces conflicts of interest in determining whether to engage in such wall crossings. Information obtained in connection with such wall crossings may limit or restrict the ability of the investment adviser to engage in or otherwise effect transactions on behalf of the Fund(s) (including purchasing or selling securities that the investment adviser may otherwise have purchased or sold for a Fund in the absence of a wall crossing).

Calvert Emerging Markets Focused Growth Fund35Prospectus dated May 1, 2024

Additional Tax Information

The Fund intends to pay distributions annually. Distributions may not be paid if Fund (and/or Class) expenses exceed Fund income for the period. Different Classes of the Fund will generally distribute different amounts. The Fund intends to distribute any net realized capital gains (if any) annually. It may also be necessary, in order to qualify for favorable tax treatment and to avoid any Fund-level tax, for the Fund to make a special income and/or capital gains distribution at the end of the calendar year.

Distributions of the Fund’s investment income and net realized short-term capital gains will generally be taxed as ordinary income. Distributions of net gains from investments held for more than one year generally will be taxed as long-term capital gains. Taxes on distributions of capital gains are determined by how long the Fund owned (or is treated as having owned) the investments that generated them, rather than how long a shareholder has owned his or her shares in the Fund. Distributions of investment income properly reported by the Fund as derived from “qualified dividend income” (as further described in the SAI) will be taxed in the hands of individuals at rates applicable to long-term capital gain provided holding period and other requirements are met by both the shareholder and the Fund. Over time, distributions by the Fund can generally be expected to include ordinary income, qualified dividend income and capital gain distributions taxable as long-term capital gains. A portion of the Fund’s income distributions may be eligible for the dividends-received deduction for corporations. The Fund’s distributions will be taxable as described above whether they are paid in cash or reinvested in additional shares. As long as a return of capital does not exceed a shareholder’s cost basis in its shares, it generally will not be taxable to the shareholder but will reduce the cost basis of the shareholder’s shares and result in a higher reported capital gain or a lower reported capital loss on a subsequent taxable disposition of such shares.

Investors who purchase shares at a time when the Fund’s net asset value reflects gains that are either unrealized or realized but not distributed will pay the full price for the shares and then may receive some portion of the purchase price back as a taxable distribution. Certain distributions paid in January may be taxable to shareholders as if received on December 31 of the prior year. A redemption of Fund shares, including an exchange for shares of another fund, is generally a taxable transaction.

Calvert Emerging Markets Focused Growth Fund36Prospectus dated May 1, 2024

The net investment income of certain U.S. individuals, estates and trusts is subject to a 3.8% Medicare contribution tax. For individuals, the tax is on the lesser of “net investment income” and the excess of modified adjusted gross income over certain threshold amounts. Net investment income includes, among other things, interest, dividends and capital gains derived from passive activities and trading in securities or commodities. Net investment income is reduced by deductions “properly allocable” to this income.

The Fund expects to send shareholders a statement each February showing the tax status of all distributions for the prior calendar year.

Investments in foreign securities may be subject to foreign withholding taxes or other foreign taxes with respect to income (possibly including, in some cases, capital gains) which may decrease the Fund’s yield on such securities. These taxes may be reduced or eliminated under the terms of an applicable tax treaty. In addition, investments in foreign securities or foreign currencies may increase or accelerate the Fund’s recognition of ordinary income and may affect the timing or amount of the Fund’s distributions.

Under certain circumstances, shareholders may be entitled to claim a credit or deduction with respect to foreign taxes paid by the Fund. If more than 50% of the Fund’s assets at taxable year end consists of securities of foreign corporations, the Fund will be eligible to and generally intends to file an election for such taxable year, which would require Fund shareholders to include in gross income their pro rata share of qualified foreign taxes paid by the Fund (even though such amounts are not received by the shareholders) and could allow Fund shareholders, provided certain requirements are met, to use their pro rata portion of such foreign income taxes as a foreign tax credit against their U.S. federal income taxes or, alternatively, for shareholders who itemize their tax deductions, to deduct their portion of the Fund’s foreign taxes paid in computing their taxable income for U.S. federal income tax purposes. However, even if the Fund qualifies to make such an election for any year, it may determine not to do so.

The Fund may be required to withhold, for U.S. federal income tax purposes, a portion of the dividends, distributions and redemption proceeds payable to shareholders who fail to provide the Fund with their correct taxpayer identification number or make required certifications, or who have been notified by the Internal Revenue Service (“IRS”) that they are subject to backup withholding. Certain shareholders are exempt from backup withholding. Backup withholding is not an additional tax and any amount withheld may be credited against a shareholder’s U.S. federal income tax liability.

Shareholders should consult with their tax advisors concerning the applicability of U.S. federal, state, local and other taxes, including non-U.S. taxes, to an investment.

Calvert Emerging Markets Focused Growth Fund37Prospectus dated May 1, 2024

Financial Highlights

The financial highlights are intended to help you understand the Fund’s financial performance for the period(s) indicated. Certain information in the table reflects the financial results for a single Fund share. The total returns in the table represent the rate an investor would have earned (or lost) on an investment in the Fund (assuming reinvestment of all distributions at net asset value). This information has been audited by Deloitte & Touche LLP, an independent registered public accounting firm. The report of Deloitte & Touche LLP and the Fund’s financial statements are incorporated herein by reference and included in the Fund’s annual report, which is available upon request.

	Period Ended December 31,
	2023(1)
	Class A	Class C	Class I	Class R6
Net asset value - Beginning of period	$10.00	$10.00	$10.00	$10.00
Income (Loss) From Operations
Net investment income (loss)(2)	$0.02	$(0.03)	$0.03	$0.03
Net realized and unrealized gain	1.22	1.22	1.22	1.22
Total income from operations	$1.24	$1.19	$1.25	$1.25
Less Distributions
From net investment income	$—	$—	$(0.01)	$(0.01)
Total distributions	$—	$—	$(0.01)	$(0.01)
Net asset value – End of period	$11.24	$11.19	$11.24	$11.24
Total Return(3)(4)	12.40%	11.90%	12.53%	12.54%
Ratios/Supplemental Data
Net assets, end of period (000’s omitted)	$56	$56	$5,460	$56
Ratios (as a percentage of average daily net assets):(5)
Total expenses(6)	5.64%	6.39%	5.40%	5.39%
Net expenses(6)(7)	1.24%	1.99%	0.99%	0.99%
Net investment income (loss)(6)	0.30%	(0.45)%	0.55%	0.55%
Portfolio Turnover(4)	29%	29%	29%	29%

(1)For the period from the commencement of operations, May 31, 2023, to December 31, 2023.

(2)Computed using average shares outstanding.

(3)Returns are historical and are calculated by determining the percentage change in net asset value with all distributions reinvested and do not reflect the effect of sales charges, if any.

(4)Not annualized.

(5)Total expenses do not reflect amounts reimbursed and/or waived by the adviser and certain of its affiliates, if applicable. Net expenses are net of all reductions and represent the net expenses paid by the Fund.

(6)Annualized.

(7)Includes a reduction by the investment adviser of a portion of its advisory fee due to the Fund’s investment in the Liquidity Fund (equal to less than 0.005% of average daily net assets for the period ended December 31, 2023).

Calvert Emerging Markets Focused Growth Fund38Prospectus dated May 1, 2024