Emotions undeniably play a central role in world politics. Fear is at the heart of realism, driving security dilemmas. Trust is typically required for cooperation in the liberal international order. Overconfidence leads to suboptimal group decision making. And emotional contagion helps make sense of identity formation and its changing nature in constructivism. Despite featuring prominently in theories of international relations, the study of emotions themselves has been historically marginalized in the field, for a variety of reasons. One reason for this lack of specific engagement with emotions is the deep-rooted belief commonly found in the first wave of emotions research that,asAndrewA.G.Rossputsit, emotions are “periodic aberrations from some baseline of ‘rational’competency”(p. 151). This book, by theorizing emotions in a serious, deep, and multidisciplinary way, where rationality is not an enemy, not only provides a corrective to this mistaken duality in which emotions and rationality are set apart and never the twain shall meet, but also it sets forth a fresh account of emotions that will likely shape the future of emotions, and affect research in international relat