This book sets out a philosophical and practical account of contemporary global politics from a cosmopolitan point of view. The volume begins by developing a theory of cosmopolitanism, explicating its core principles and justifications. The role many of these principles have had in global politics is then explored; they have been important in framing the human rights regime and several aspects of international law and politics. The book then examines how legal and institutional developments at the global level fall short of cosmopolitan ideals. The argument is that this deficit is not inevitable, and can be overcome over time through an ambitious and yet practical agenda of reform. In the second half of the book, chapters are devoted to some of the most pressing issues of our time - financial market crises, climate change, and the fallout from the wars in Afghanistan and Iraq. In each of these areas, the author argues that realist politics is exhausted, and that cosmopolitanism is the new realism. In short, the book offers a novel approach to thinking about global politics and case studies of its application by one of the best known authors in the field.