These are the nation’s ten most influential think tanks, according to a study by University of Pennsylvania professor James McGann. All salary figures are from 2008. Here are some of the nation's biggest thinkers.
The Brookings Institution, led since 2002 by former deputy secretary of State Strobe Talbott. Salary: $425,000
The Carnegie Endowment for International Peace, led since 1997 by Jessica Tuchman Mathews, former head of the World Resources Institute environmental think tank. Salary: $542,155.
The Council on Foreign Relations, led since 2003 by Richard Haass, head of policy planning under Secretary of State Colin Powell. Salary: $664,000.
The Rand Corporation, led by James Thomson, a former nuclear physicist and Pentagon official. Salary: $554,727.
The Heritage Foundation, led since 1977 by Ed Feulner. Salary: $947,999.
The Center for Strategic and International Studies, led by John Hamre, deputy secretary of Defense under President Clinton. Salary: $418,544.
The Cato Institute, led by founder Edward Crane. Salary: $438,750.
The Woodrow Wilson International Center for Scholars, led by Lee Hamilton, a former Indiana congressman and vice chair of the 9/11 Commission. Salary: $371,856.
The American Enterprise Institute, led since 2009 by Arthur Brooks, who was a business and government professor at Syracuse University. Salary of his predecessor: $675,000.
The Hoover Institution, part of Stanford University, led by John Raisian, a government economist with the federal government. Salary not available.