Documentation of American intellectual life since the end of World War II includes the papers of Nobel laureate economist Milton Friedman and distinguished physicist Edward Teller, philosophers Sidney Hook and Eric Hoffer, sociologist Seymour Martin Lipset, economic historian and sociologist Karl A. Wittfogel, historian Bertram D. Wolfe, and novelist Allen Drury.

Among the American radicals represented are Jay Lovestone, a founder of the U.S. Communist Party and later an anticommunist labor leader; Benjamin Gitlow, a cofounder of the Communist Labor Party; and Joseph Hansen, one of the top leaders of the U.S. Socialist Workers Party and a former secretary to Leon Trotsky. In addition, the Hoover Institution houses the international archives of the Socialist Workers Party, one of the world's most influential Trotskyist parties of recent decades.

Major economists whose papers are in the archives are Fritz Machlup, Benjamin S. Rogge, Dan Throop Smith, Murray L. Weidenbaum, Roger A. Freeman, and William A. Niskanen. The archives is also a repository for the Mont Pelerin Society records, an international organization of economists, public figures, and journalists for the study of free market systems.