This article reviews the huge Cold War-era and post-Cold War literature on American Communism and anti-Communism in the United States. These issues have long been the subject of heated scholarly debate. The recent opening of archives in Russia and other former Communist countries and the release of translated Venona documents in the United States have shed new light on key aspects of the American Communist Party that were previously unknown or undocumented. The new evidence has underscored the Soviet Union's tight control of the party and the crucial role that American Communists played in Soviet espionage. The release of all this documentation has been an unwelcome development for scholars who have long been sympathetic to the Communist movement.