EXHIBIT 21

SUBSIDIARIES OF THE REGISTRANT

Whitcomb Investments, Inc., a Massachusetts corporation

Forrester Middle East FZ-LLC, a Dubai, United Arab Emirates corporation

Forrester Research, B.V., a Dutch corporation

Forrester Research Limited, a United Kingdom corporation

Forrester Research KK, a Japanese corporation

Forrester Research Australia Pty. Ltd., an Australian corporation

Forrester Research (Canada) Inc., a New Brunswick, Canadian corporation

Forrester Research GmbH & Co. KG, a German partnership

Forrester Verwaltungs GmbH, a German corporation

Forrester Beteiligungs GmbH, a German corporation

Forrester Research GmbH, a Swiss corporation

Forrester Research India Private Limited, an Indian corporation

Forrester Research Israel Limited, an Israeli corporation

Forrester Research SAS, a French corporation

Forrester Research APS, a Danish corporation

Forrester Research S.r.l., an Italian corporation

Giga Information Group Limited, a United Kingdom corporation

JupiterResearch, Ltd., a United Kingdom corporation