Both a directory of U.S. and international think tanks, as well as a custom Google search of more than 250 think tank websites.

Think Tank Search is a custom Google search of more than 470 think tank websites. For the purposes of this search, think tanks are defined as institutions affiliated with universities, governments, advocacy groups, foundations, non-governmental organizations, and businesses that generate public policy research, analysis, and activity. Inclusion is based upon the relevancy of subject area to HKS coursework and scholarship, the availability of the think tank’s research in full-text on the website, and the think tank’s reputation and influence upon policy making. The list represents a mixture of partisan and non-partisan think tanks.