EXHIBIT 99.1



                            CERTIFICATION PURSUANT TO
            SECTION 1350, CHAPTER 63 OF TITLE 18, UNITED STATES CODE,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to Section 1350, Chapter 63 of Title 18, United States Code, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, the undersigned, as
Chief Executive Officer of Forrester Research, Inc. (the "Company"), does hereby
certify that to the undersigned's knowledge:

      1)    the Company's Annual Report on Form 10-K for the year ended December
            31, 2002 fully complies with the requirements of Section 13(a) or
            15(d) of the Securities Exchange Act of 1934; and

      2)    the information contained in the Company's Annual Report on Form
            10-K for the year ended December 31, 2002 fairly presents, in all
            material respects, the financial condition and results of operations
            of the Company.
                                  /s/  George F. Colony
                                  -------------------------------
                                  George F. Colony
                                  Chairman of the Board of Directors and Chief
                                  Executive Officer


Dated: March 31, 2003