In this paper, Nathan Moore explores the complicated question of how American communists responded to the Soviet Union’s 1939-1940 invasion of Finland, and reveals its long-lasting consequences in American political discourse. Using clear and concise prose, Moore painstakingly examines the reactions of the Communist Party of the United States, the Socialist Workers Party Majority, and the Socialist Workers Party Minority to the Winter War and argues that each faction’s response depended on how it defined ‘imperialism.’ Drawing on detailed analyses of primary source documents, this paper constitutes an original contribution to the literature on the international impact of the Winter War. -Meghan Riley