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 quarterly
                  period ended June 30, 2003 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 quarterly period ended June 30, 2003
                  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: August 14, 2003

A signed original of this written statement required by Section 906 has been
provided to Forrester Research, Inc. and will be retained by Forrester Research,
Inc. and furnished to the Securities and Exchange Commission or its staff upon
request.