Exhibit 99.1

NEWS RELEASE

ICF Reports Third Quarter 2026 Results

―Third Quarter Marks Return to Year-on-Year Revenue Growth―

―Revenue from Federal Government Clients Increased 3.4% Sequentially―

―Margin Expansion Benefited from Efficient Contract Delivery and Favorable Contract Mix―

―Maintains 2026 Non-GAAP EPS Guidance Midpoint on Lower Revenue―

Third Quarter Highlights:

RESTON, Va., November 5, 2026 -- ICF (NASDAQ: ICFI), a global consulting and technology services provider, reported results for the third quarter ended September 30, 2026.

Management Commentary

John Wasson, chair and chief executive officer, said, “Our third quarter performance demonstrated the return to year-on-year revenue growth that we anticipated would begin in the second half of this year and benefited from our diversified and integrated business model. Revenues from our federal government clients continued to show solid sequential growth in line with our expectations, and revenues from state and local and non-U.S. government clients increased 7.6% and 12.0% year-on-year, respectively.

“A key highlight of the third quarter was our strong margin performance, benefiting from efficient contract delivery and favorable contract mix. Our Adjusted EBITDA margin was 11.5%, expanding by 10 basis points year-on-year and representing a notable sequential increase. Fixed-price contracts accounted for 50.2% of our third quarter revenues, up from 48.7% in the similar period last year, and together with time & material contracts represented 94.3% of this quarter’s revenues. We are closely managing corporate costs, while continuing to invest in technology and professional staff to support client programs and capture new business opportunities.

“Third quarter revenues from commercial energy clients were considerably below our expectations due to a confluence of factors, most notably a sharp fall-off in contract add-on activity that historically has bolstered second half revenues in our utility programs category. There was a material increase in political and regulatory pressure on utilities in Q3 to develop affordable solutions for their customers, which has caused a slowdown and/or shift in incremental spending priorities for certain existing utility programs. Also, we experienced slower than expected ramp-ups on new contracts. As a result, ICF’s revenues from commercial energy clients are expected to increase at a low- to mid-single-digit rate for 2026. We continue to see commercial energy as a long-term growth driver for ICF. Our year-to-date contract awards have been strong, our win rates are increasing, and we are building a meaningful pipeline in areas where we see utility spending expanding, including audits/weatherization, demand response and virtual power plants.

“This also was a strong quarter for companywide contract awards, which increased 4.5% year-on-year to $746 million. Over 60% of our third quarter awards represented new business, a good indication of how well ICF’s capabilities and expertise are aligned with our clients’ priorities. Following this solid performance, our business development pipeline stood at $8.2 billion at the end of the third quarter and was well diversified across our client set.”

Third Quarter Business Highlights in Key Long-Term Growth Markets

Commercial Energy

ICF manages over 300 energy efficiency programs for 60 utilities in 28 states. Revenues from this part of the company’s commercial energy business were similar to last year’s levels due to the near-term challenges described above. We continue to see positive underlying momentum supported by year-to-date contract wins and client demand for our expertise as they address affordability issues together with operational imperatives around electrification and data center requirements. Energy advisory revenues increased 14.1% in the quarter and 10.5% year-to-date, with particular strength in our work on grid engineering and planning, transmission and interconnection, integrated power and gas planning, resource adequacy, technical due diligence, and storage. Additionally, our work with hyperscalers is expanding, and we are advising on a broader set of issues created by the scale of data center development, including energy efficiency, community impacts, power supply and reliability. As anticipated, other commercial energy comparisons declined year-on-year due to the wind-down of several wind energy projects through last year's third quarter.

Commercial energy awards represented approximately 26% of year-to-date contract awards, and commercial energy opportunities represent more than $1.6 billion of our pipeline at the end of the third quarter.

ICF’s energy work includes programs for federal and state agencies that provide us with greater insight into the regulatory and stakeholder environment, which strengthens our ability to meet and often exceed the milestones of our commercial energy contracts.

Technology Modernization

ICF has built out its technology modernization capabilities over the last six years, which in the third quarter represented approximately 50% of our revenues from federal government clients. Over 80% of ICF’s technology modernization work is performed under outcome-based, fixed-price contracts, the preferred contract vehicles for government technology projects. Additionally, we continue to align our federal portfolio around administration priorities, with increased focus on expanding our footprint in the defense and national security arena, while building our brand in government-wide application modernization.

While primarily serving federal agency clients, our technology modernization capabilities are deployed across the company’s client categories. Technology modernization opportunities represented approximately $2.4 billion of our pipeline at the end of the third quarter.

State and Local Government/Disaster Recovery

The 7.6% revenue growth from state and local government clients in the third quarter illustrates ICF’s ability to leverage its deep domain expertise and robust technology capabilities across its client sets. Several of the projects driving growth in this client category include developing and managing energy efficiency programs in the Northeast and California, providing advanced technology solutions to several states and territories, and offering our rural health services.

During the quarter, ICF supported more than 50 active disaster recovery programs in more than 20 states and territories. While we view the disaster management market as a driver of long-term growth, funding delays and the slower pace of major events have constrained near-term activity in this arena. ICF continues to execute substantial rebuilding and mitigation projects utilizing our environmental and climate expertise, and we are helping our clients prepare to take on a larger role in rebuilding and resilience, having significantly increased our on-call contracts with state and local governments. State and local government opportunities represented approximately $1.1 billion of the total pipeline at the end of the third quarter.

Third Quarter 2026 Financial Results

Third quarter 2026 total revenue was $470.5 million, up 1.1% from the $465.4 million reported in the third quarter of 2025. Subcontractor and other direct costs were 23.6% of total revenues, compared to 24.2% in last year’s third quarter. Gross margin was 38.1%, 50 basis points above the prior year period. Operating income was $43.6 million, up 13.6% from $38.4 million, and operating margin expanded by 100 basis points to 9.3% from 8.3% in the prior year period. Net income totaled $31.7 million, or $1.76 per diluted share, up from net income of $23.8 million, or $1.28 per share reported in the third quarter of 2025, benefiting from a tax rate of 15.0% and a lower share count. In the prior year quarter, the company’s tax rate was 22.7%.

Non-GAAP EPS increased 18.6% to $1.98 per share, benefiting from the lower tax rate and share count mentioned above. EBITDA was $53.6 million, up from $52.8 million reported in the year-ago quarter. Adjusted EBITDA was $54.2 million, and Adjusted EBITDA margin on total revenues was 11.5%, compared to 11.4% in the third quarter of 2025.

Cash flows from operations were $35.2 million in this year’s third quarter. Excluding restricted cash mainly tied to energy efficiency programs, which fluctuates with the timing of incentive payments to utility customers, operating cash flow was $45.5 million, up from $17.3 million reported in the comparable prior year period. For the first nine months of 2026, cash flows from operations were $131.7 million. Excluding restricted cash, year-to-date operating cash flows were $88.7 million, up from $30.2 million in the first nine months of 2025, on a similarly adjusted basis.

Backlog and New Business

Total backlog was $3.5 billion at the end of the third quarter of 2026. Funded backlog was $1.8 billion, or approximately 52% of the total backlog. The total value of contracts awarded in the 2026 third quarter was $746 million for a quarterly book-to-bill ratio of 1.59 and trailing twelve-month contract awards totaled $2.0 billion for a book-to-bill ratio of 1.11.

Commercial Revenue Third Quarter 2026 Highlights

Commercial revenue was $158.8 million during the quarter, up 1.5% year-over-year.

Key Commercial Contracts Awarded in the Third Quarter of 2026

Notable commercial contract awards won in the third quarter of 2026 included:

Government Revenue Third Quarter 2026 Highlights

Revenue from government clients was $311.7 million during the quarter.

Key Government Contracts Awarded in the Third Quarter of 2026

Notable government contract awards won in the third quarter of 2026 included:

Dividend Declaration

On November 5, 2026, ICF declared a quarterly cash dividend of $0.14 per share, payable on January 8, 2027, to shareholders of record on December 4, 2026.

Summary and Outlook

“ICF is on the path to second half year-on-year revenue growth, and we see positive momentum as we head into 2027. The adjusted EBITDA margin expansion we achieved in the third quarter was notable, our new contract awards were strong, and our business development pipeline is robust, all indications of the underlying strength of our business and effective cost management. Additionally, given ICF’s diversified portfolio, we see the midterm election results as a tailwind for our business.

“For full year 2026, we are expecting revenues to be similar to 2025 levels, with GAAP EPS of approximately $5.95, inclusive of $.11 of special charges. We are maintaining the midpoint of our Non-GAAP EPS guidance range of $7.10, representing 4.9% year-on-year growth and benefiting from improved margins, a lower interest rate and reduced share count. Operating cash flow is expected to range from $135 million to $150 million, excluding the impact of restricted cash.

“We continue to benefit from the energy of our people, who have shown tremendous dedication and commitment to our clients and embody the strong corporate culture that ICF is known for,” Mr. Wasson concluded.

1 Non-GAAP EPS, EBITDA and Adjusted EBITDA are non-GAAP measurements. A reconciliation of all non-GAAP measurements to the most applicable GAAP number is set forth below. Special charges are items that were included within our consolidated statements of comprehensive income but are not indicative of ongoing performance and have been presented net of applicable U.S. GAAP taxes. The presentation of non-GAAP measurements may not be comparable to other similarly titled measures used by other companies.

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About ICF

ICF is a leading global solutions and technology provider. At ICF, business analysts and policy specialists work together with digital strategists, data scientists and creatives. We combine unmatched industry expertise with cutting-edge engagement capabilities to help organizations solve their most complex challenges. Since 1969, public and private sector clients have worked with ICF to navigate change and shape the future. Learn more at icf.com.

Caution Concerning Forward-looking Statements

Statements that are not historical facts and involve known and unknown risks and uncertainties are "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995, as amended. Such statements may concern our current expectations about our future results, plans, operations and prospects and involve certain risks, including those related to: the government contracting industry generally; our dependence on contracts with U.S. federal, state and local, and international government clients for the majority of our revenue; failure by Congress or other governmental bodies to approve budgets and appropriations in a timely fashion, reductions in government spending, and the impact of a lengthy federal government shutdown; the current Administration’s policy changes, executive orders, and failure to spend Congressionally mandated appropriations, including the resulting effect on government audits and contract terminations; changes in federal government budgeting and spending priorities; our ability to estimate and control costs under our fixed-price contracts; the realization of our backlog; the dependence of our commercial work on sectors of the global economy that are highly cyclical; and our ability to acquire and successfully integrate businesses. These and other factors that could cause our actual results to differ materially from those indicated in our forward-looking statements are described in the "Risk Factors" section of our Annual Report on Form 10-K for the year ended December 31, 2025, and in our subsequent filings with the Securities and Exchange Commission. The forward-looking statements included herein are made only as of the date hereof, and we specifically disclaim any obligation to update these statements in the future.

Note on Forward-Looking Non-GAAP Measures

The company does not reconcile its forward-looking non-GAAP financial measures to the corresponding U.S. GAAP measures, due to the variability and difficulty in making accurate forecasts and projections and because not all of the information necessary for a quantitative reconciliation of these forward-looking non-GAAP financial measures (such as the effect of share-based compensation or the impact of future extraordinary or non-recurring events like acquisitions) is available to the company without unreasonable effort. For the same reasons, the company is unable to estimate the probable significance of the unavailable information. The company provides forward-looking non-GAAP financial measures that it believes will be achievable, but it cannot accurately predict all of the components of the adjusted calculations, and the U.S. GAAP financial measures may be materially different than the non-GAAP financial measures.

Investor Contacts:

Lynn Morgen, ADVISIRY PARTNERS, lynn.morgen@advisiry.com +1.212.750.5800

David Gold, ADVISIRY PARTNERS, david.gold@advisiry.com +1.212.750.5800

Company Information Contact:

Lauren Dyke, ICF, lauren.dyke@ICF.com +1.571.373.5577

ICF International, Inc. and Subsidiaries

Consolidated Statements of Comprehensive Income

(Unaudited)

ICF International, Inc. and Subsidiaries

Reconciliation of Non-GAAP Financial Measures(2)

(Unaudited)

ICF International, Inc. and Subsidiaries

Consolidated Balance Sheets

ICF International, Inc. and Subsidiaries

Consolidated Statements of Cash Flows

(Unaudited)

ICF International, Inc. and Subsidiaries

Supplemental Schedule (11)

(11) As is shown in the supplemental schedule, we track revenue by key metrics that provide useful information about the nature of our operations. Client market provide insight into the breadth of our expertise. Client type is an indicator of the diversity of our client base. Revenue by contract mix provides insight in terms of the degree of performance risk that we have assumed.