Holdings on World War II and the build-up to the war are extensive. They include the papers of Stanley K. Hornbeck (chief adviser on the Far East in the Department of State, 1928–1944), Maxwell Hamilton (chief of the Division of Far Eastern Affairs, 1937–1943), and Jay Calvin Huston (consul in China, 1917–1932).

The Archives holds the papers of both General Joseph W. Stilwell, commander of U.S. forces in China, Burma, and India during much of World War II, and of General Albert C. Wedemeyer, who replaced Stilwell as commanding general of that theater in 1944. The Robert D. Burhans papers delineate the activities of the First Special Service Force, 1941–1944. The papers of Major General Frank S. Ross, former chief of transportation for the European theater in World War II, treat the problem of logistics in the prosecution of the war. The diaries of Professor Hubert G. Schenck cover the years he served on General MacArthur's staff in Tokyo and as director of the Economic Cooperation Administration program in Taiwan. Another notable military figure represented is Lieutenant General Claire Lee Chennault, head of the Flying Tiger volunteer group in China and adviser to Chiang Kai-shek. Papers of several American pilots flying for the British Air Transport Auxiliary document this international effort to ferry aircraft from factories to squadrons during the war.

The America First Committee records provide insight into the attitudes of some U.S. citizens toward the participation of their country in the war, and the records of the War Relocation Authority and the National Japanese American Student Relocation Council document the transfer of the Japanese population on the Pacific Coast to relocation centers. Postwar U.S. broadcasting activities of Radio Free Europe and Radio Liberty are covered by extensive broadcast and corporate records of RFE/RL, Inc.