International Relations (IR) theorists speak with conviction, and often passion, to the global condition of human society. The result is an important, dynamic and often deeply divided field. This long-awaited new edition of International Relations Theory Today offers undergraduate and postgraduate students an essential guide to the complex terrain of IR theory and the key questions on its agenda. With chapters by 25 prominent and provocative IR theorists, the book reveals the intellectual excitement - and turmoil - of theorizing world politics. It reflects the conflicts and tensions around the profound challenges facing the contemporary world, such as climate change, globalization, nuclear proliferation, and economic and political injustice and conflict, while also expressing hope that we can better understand, and respond to, these challenges. Above all, this book demonstrates the significance of thinking theoretically about international relations and developing the tools not merely to describe but also to explain, analyse, prescribe and possibly re-imagine the global political landscape. As the world comes face-to-face with historic challenges over the coming decades, International Relations Theory Today will help its readers to participate more effectively in debates about the most important global political dilemmas of our time.