Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 27, 2018
Document and Entity Information
Entity Registrant Name	CRA INTERNATIONAL, INC.
Entity Central Index Key	0001053706
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-29
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		8,079,661
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1