Publisher's Note This study traces the origins and development of Kropotkin's ideas and revolutionary practice from 1872 to 1886, and assesses the subsequent influence of his life and work on European radical and socialist movements. The author analyzes Kropotkin's role in the transformation of Bakunin's anti-authoritarian socialism, and shows how two principle types of revolutionary action emerged from anarchist efforts to develop clear alternatives to the parliamentary strategies of social democrats; one based on the activities of individuals and small groups; the other related to large-scale collective action. Her general conclusion is that previous assumptions about Kropotkin's disregard of the potential revolutionary role of the labor movement have been misplaced, and that his concept of revolutionary action was far broader and more high-minded than the notorious slogan of propaganda by deed might suggest.