This book assesses the concepts of the state and sovereignty in international relations. The concept of the state plays a central role in international relations, particularly in realist and neo realist approaches. Yet, the meaning of the state is taken to be self evident by both its advocates and its critics. This volume counters this trend. It systematically considers the nature of the state, the concept of sovereignty and the challenges of globalisation and cosmopolitanism. Featuring contributions from some of the most reputed theorists of the state, the essays in this collection give you a coherent and, at the same time, distinctively pluralist set of original reflections on the role and nature of the state. It is written by a transatlantic mix of scholars, many with established reputations in the field. It strongly focuses on the nature of the state and sovereignty. It opens up wider debates about these concepts, which will stimulate new research.