This book provides both an introduction to utopianism and a general perspective on radical political thought. Vigorously disputing the widespread conviction that utopianism is a fantasy with no relevance to modern political life and thought, the authors argue that it is a concept whose special virtue lies in its capacity to transcend the limitations of present circumstances, to inspire alternative thinking and to open up new directions for political action. This book develops an approach which relates social causes to political theory and practice. The first part discusses utopianism as a form of political theory with unique characteristics and the ability to transcend the present. The second part considers utopianism as an expression of fundamental social impulses and as an ingredient of modern political movements. The third part offers a defence of utopianism as both theory and practice, and argues for its use to counteract the pragmatism and narrow empiricism which often passes for political "realism" in modern societies. This reissue of a popular and well-received landmark text contains a new preface.