EXHIBIT 32.1



                            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 Quarterly Report on Form 10-Q for the three months ended
    September 30, 2004 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 Quarterly Report on Form 10-Q
    for the three months ended September 30, 2004 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: November 8, 2004