Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Mar. 04, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	FORR
Entity Registrant Name	Forrester Research, Inc.
Entity Central Index Key	0001023313
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		19,394,000
Entity Public Float			$ 340,000,000
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity File Number	000-21433
Entity Tax Identification Number	04-2797789
Entity Address, Address Line One	60 Acorn Park Drive
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02140
City Area Code	617
Local Phone Number	613-6000
Title of 12(b) Security	Common Stock, $0.01 Par Value
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction Flag	false
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238