War has been a key topic of speculation and theorising ever since the invention of philosophy in classical antiquity. This anthology brings together the work of distinguished contemporary political philosophers and theorists who address the leading normative and conceptual issues concerning war. The book is divided into three parts: initiating war, waging war, and ending war. The contributors aim to provide a comprehensive introduction to each of these main areas of dispute concerning war. Each essay is an original contribution to ongoing debates on various aspects of war and also provides a survey of the main topics in each subfield. Serving as a companion to the theoretical issues pertaining to war, this volume also is an important contribution to debates in political philosophy. It can serve as a textbook for relevant courses on war offered in philosophy departments, religious studies programs, and law schools.