A group of Central European communists, most of them Hungarians, in the interwar period served the world communist movement as international cadres of the Comintern, the Moscow-based Communist International. As an important member of this cohort, József Pogány played a major role in the Hungarian Soviet Republic of 1919, the "March Action" in Germany in 1921, and, under the name of John Pepper, in the development of the American Communist Party of the 1920s. During the 1920s he was an important official in the Comintern apparatus and undertook missions on three continents. A prolific writer and effective organizer, he was one of the most flamboyant and controversial communists of his era. Some of his comrades praised him as "the Hungarian Christopher Columbus." Others, like Trotsky, called him a "political parasite."This study is based on newly available primary sources from Hungary, Russia, and the United States; it is the first ever written about this colorful and well-travelled Hungarian communist. Examines Pogány's development as a socialist and communist, the influence of his Jewish origins on his career, the reasons for his remarkable success in the United States, and the circumstances that led to his arrest and execution in the Stalinist terror.