First published in 1979. Elisée Reclus was an important anarchist theorist whose contribution to the radical direction which the European anarchist movement assumed in the late nineteenth century, has been largely neglected by scholars. This study of his thought provides a basis for a general re-assessment of European anarchism, by contributing to an understanding of important dimensions of theory and practice, which previously have not been well understood. Amongst the aspects examined are the anarchist conception of the state, the nature of oppression and revolution and the role of violence and terrorism. One of the revealing and fundamental themes of this examination, is that the social and political theory of Elisée Reclus was the product of interaction of utopianism and science, two strands of thought frequently taken to be mutually exclusive. For Reclus the use of the scientific method served to strengthen his concept of Utopia, rendering it part of the real world. Within this context of utopianism and science, it can be seen that Reclus’ legendary benevolence, and his justification of violence are logically consistent, both deriving from his all-embracing social and political theory. This work presents a challenging approach to many widely held views about the nature of anarchism, particularly regarding its relationship to socialism.