Since the publication of James Fearon’s seminal ‘Rationalist Explanations for War’, the bargaining model has been the dominant theoretical approach to the onset, duration, and termination of war. A huge range of formal models have been published examining why actors (such as states or dissident groups) make decisions that lead them to start, or continue, wars. These models have shown that some existing explanations of war are not logically consistent, and revealed important new insights into the conditions under which wars happen. Spaniel’s book provides an excellent overview of this literature, in a form that is accessible to a wide range of audiences, including undergraduates, graduate students, and scholars. It begins with a basic model of crisis bargaining, and then through subsequent chapters examines the conditions under which war can occur in this model. The book is broadly divided into a focus on complete information models and incomplete information models and shows various pathways to war in each. I found the presentation of each part very clear, and it helped to clarify my own understanding of different types of commitment problems and the role they can play in conflict onset. In addition, each chapter contains exercises students can use to further their understanding of the models themselves and the dynamics they reveal. I would have liked to see a bit more focus on the insights of these models for conflict duration and termination, but the book covers an incredible amount already. I will assign parts of it to undergraduates, recommend it to graduate students, and refer to it often in my own theoretical work.