SEC Form DEFA14A filed by CRA International Inc.

Step 1: Go to www.envisionreports.com/CRAI. Step 2: Click on Cast Your Vote or Request Materials. Step 3: Follow the instructions on the screen to log in. www.envisionreports.com/CRAI Online Go to www.envisionreports.com/CRAI or scan the QR code — login details are located in the shaded bar below. Shareholder Meeting Notice 03ZWUB + + Important Notice Regarding the Availability of Proxy Materials for CRA International, Inc.’s Shareholder Meeting to be Held on July 18, 2024 Under Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual shareholders’ meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on and location of the annual meeting are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The Notice of Annual Meeting of Shareholders, 2024 Proxy Statement and 2023 Annual Report to Shareholders will be, on or prior to May 31, 2024, available at: Obtaining a Copy of the Proxy Materials – If you want to receive a copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. Please make your request as instructed on the reverse side on or before July 2, 2024 to facilitate timely delivery. 2NOT Easy Online Access — View your proxy materials and vote. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials. Step 4: Make your selections as instructed on each screen for your delivery preferences. Step 5: Vote your shares. Votes submitted electronically must be received by July 18, 2024 at 1:00 A.M., local time. MMMMMMMMMMMM MMMMMMMMM 1234 5678 9012 345 C 1234567890 COY MMMMMMM 000001MR A SAMPLE DESIGNATION (IF ANY) ADD 1 ADD 2 ADD 3 ADD 4 ADD 5 ADD 6 ENDORSEMENT_LINE______________ SACKPACK_____________

Here’s how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. — Internet – Go to www.envisionreports.com/CRAI. Click Cast Your Vote or Request Materials. — Phone – Call us free of charge at 1-866-641-4276. — Email – Send an email to [email protected] with “Proxy Materials CRA International, Inc.” in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, requests for a paper copy of proxy materials must be received by July 2, 2024. CRA International, Inc.’s Annual Meeting of Shareholders will be held on July 18, 2024, 8:00 A.M. local time at the offices of CRA International, Inc., located at 200 Clarendon Street, 9th Floor, Boston, Massachusetts 02116 Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board of Directors recommends a vote FOR the listed nominees as Class II Directors and FOR Proposals 2 and 3: 1. To consider and vote upon the election of three Class II Directors: 01 - Alva Taylor 02 - Heather Tookes 03 - Karen Keenan 2. To approve, on an advisory basis, the compensation paid to CRA’s named executive officers, as disclosed in the proxy statement for the 2024 meeting of its shareholders. 3. To ratify the appointment by our audit committee of Grant Thornton LLP as our independent registered public accountants for our fiscal year ending December 28, 2024. PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must go online or request a paper copy of the proxy materials to receive a proxy card. If you wish to attend and vote at the meeting, please bring this notice with you. Shareholder Meeting Notice