This volume examines the causes and consequences of nuclear postures and nonproliferation policies. The real-world importance of nuclear weapons has led to the production of a voluminous scholarly literature on the causes and consequences of nuclear weapons proliferation. Missing from this literature, however, is a more nuanced analysis that moves beyond a binary treatment of nuclear weapons possession, to an exploration of how different nuclear postures and nonproliferation policies may influence the proliferation of nuclear weapons and subsequent security outcomes. This volume addresses this deficit by focusing on the causes and consequences of nuclear postures and nonproliferation policies. It is the aim of this book to advance the development of a new empirical research agenda that brings systematic research methods to bear on new dimensions of the nuclear weapons phenomenon. Prior to the contributions in this volume, there has been little evidence to suggest that nuclear postures and policies have a meaningful impact on the spread of nuclear weapons or security outcomes. This book brings together a new generation of scholars, advancing innovative theoretical positions, and performing quantitative tests using original data on nuclear postures, nonproliferation policies, and WMD proliferation. Together, the chapters in this volume make novel theoretical, empirical, and methodological contributions to the field of nuclear weapons proliferation. This book will be of much interest to students of nuclear proliferation, international relations and security studies.