First published in 1938 by a leader of the Council Communism movement, Anton Pannekoek's Lenin as Philospher offers a classic left-wing interpretation and critique of Lenin's philosophical accomplishment and its relationship to the development of Leninism as perhaps the dominant political theory of the twentieth century. Providing a detailed discussion of the philosophical background to the Machist controversy which occasioned Lenin's Materialism and Empirio criticism, Pannekoek's study still stands as one of the most forceful and politically astute discussions of the topic available. Published here for the first time in an annotated and scholarly edition, this masterpiece of Marxist criticism is accompanied by a lengthy new introduction expanding and assessing Pannekoek's discussion and arguing for the continuing relevance of Lenin's thought for Marxism in the new millennium.