 Hook’s philosophical position was characterized by his affirmation of Marxism and activist commitment to its implementation in the United States, even as he concluded that the evidence of the failure of socialist institutions and Marxist practices in the Soviet Union had increasing weight. Even as Hook became deeply involved in the socialist and communist political movements during the late 1920s and early 1930s, the analysis of the negative evidence derivable from developments within Soviet society was reshaping his positive attitude toward Marxism. Consequently, Hook’s involvement with Marxism oscillated between his continuous exploration of Marxist theory including its historical origins and his increasing criticism of Soviet institutions and Communist Party practice. The critical approach to Soviet society and pro-Soviet movements gradually displaced the previous vindication of Marxist theory.