SCHEDULE 14(A)

(Rule 14a-101)

Information Required in Proxy Statement

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No.     )

Filed by the Registrant ☑

Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☐ Definitive Proxy Statement

☑ Definitive Additional Materials

☐ Soliciting Material Pursuant to § 240.14a-12

FORRESTER RESEARCH, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

☑ No fee required.

☐ Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1) Title of each class of securities to which transaction applies:

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(3) Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

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☐ Fee paid previously with preliminary materials.

☐ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

(1) Amount Previously Paid:

(2) Form, Schedule or Registration Statement No.:

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FORRESTER RESEARCH, INC. *** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting to Be Held on May 14, 2019. FORRESTER RESEARCH, INC. 60 ACORN PARK DRIVE CAMBRIDGE, MA 02140 See the reverse side of this notice to obtain proxy materials and voting instructions. E69579-P19480 You are receiving this communication because you hold shares in the company named above. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. Meeting Information Meeting Type: Annual Meeting For holders as of: March 20, 2019 Date: May 14, 2019 Time: 10:00 a.m., EDT Location: Meeting live via the Internet-please visit www.virtualshareholdermeeting.com/FORR2019 The company will be hosting the meeting live via the Internet this year. To attend the meeting via the Internet please visit www.virtualshareholdermeeting.com/FORR2019 and be sure to have the information that is printed in the box marked by the arrow (located on the following page). g XXXX XXXX XXXX XXXX

E69580-P19480 Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before April 30, 2019 to facilitate timely delivery. How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line. PROXY STATEMENT AND ANNUAL REPORT TO STOCKHOLDERS Proxy Materials Available to VIEW or RECEIVE: g XXXX XXXX XXXX XXXX g XXXX XXXX XXXX XXXX Before You Vote How to Access the Proxy Materials How To Vote Please Choose One of the Following Voting Methods Vote By Internet: Up to 11:59 p.m. Eastern Time on the Day Before The Meeting: Go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow (located on the following page) available and follow the instructions. During The Meeting: Go to www.virtualshareholdermeeting.com/FORR2019. Have the information that is printed in the box marked by the arrow (located on the following page) available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. g XXXX XXXX XXXX XXXX g XXXX XXXX XXXX XXXX

Voting Items 2. To ratify the selection of PricewaterhouseCoopers LLP as the Company's independent registered public accounting firm for fiscal 2019. 3. To approve, by non-binding vote, executive compensation. 1. Election of Directors Nominees: The Board of Directors recommends a vote FOR all the nominees listed, and FOR Proposals 2 and 3. 01) Jean M. Birch 02) David Boyce 03) Neil Bradford 04) George F. Colony 05) Anthony Friscia 06) Robert M. Galford 07) Gretchen Teichgraeber 08) Yvonne Wassenaar E69581-P19480

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