start here: Guide to Interest Groups and Lobbying
Think Tanks and Civil Societies Program
Provides an index of the largest and most influential think tanks around the world.
GuideStarThis link opens in a new window
Useful for finding...nonprofits, with a summary of each organization's mission and programs, financial information and IRS Form 990s.
Strategies:
Open Secrets.org (Center for Responsive Politics)
Useful for finding… Who’s giving how much to whom and trying to influence policy
Strategies:
Maplight.org
Mashup using data from Open Secrets and other reliable sources; match Congressional campaign contributions with legislators' votes on current bills; see aggregate interest group funding and where it went.
Washington Information Directory (2017-18)
Useful for finding…
Strategies:
ProQuest Congressional
Useful for finding…Legislative histories, full-text of bills and laws, hearings, committee reports, and member profiles
Strategy: To find witnesses who testified on an issue, search Congressional Publications/Advanced Search, and check only the box for hearings
National Center for Charitable Statistics
Useful for finding...nonprofits, with a summary of each organization's mission and programs, financial information and IRS Form 990s. Similar to Guidestar; also has downloadable data on the nonprofit sector in the US.
Think Tank Search
From Harvard's Kennedy School of Government library; custom Google search + list of hundreds of US and international think tanks
Think tanks are defined by the above as institutions affiliated with universities, governments, advocacy groups, foundations, non-governmental organizations, and businesses that generate public policy research, analysis, and activity.
Tips: Search these selected think tanks by keywords to find research and analysis.
If one seems most relevant to your topic, go to the home page and mine the site for publications, issues, research, and links to other organizations.
Political orientation of think tanks, per FAIR.org (2009)
Global Go To Think Tank Index (U Pennsylvania)
American Policy Directory (U Oregon)
Think Tank List (WorldPress.org)
Project Vote Smart
Strategy: Find interest group ratings by state, then issue, with links to summaries of the organizations involved
CQ's Politics in America
also in print in Perkins (1945-present)
Useful for finding…
Almanac of American Politics (National Journal)
Also in print in Perkins (1972-present)
Strategy: Ratings by 11 interest groups are given for each member; the groups are described in the Guide to Usage in the print edition.