This symposium addresses the role of wars and crises as mechanisms of international change. Over the past two decades, the international system has undergone a number of remarkable transformations, from the end of the Cold War to the emergence of an ongoing ''War on Terror,'' and from the collapse of statist development models to the emergence of a contested-if evolving-neoliberal ''Washington Consensus.'' This volatility exceeds any underlying shifts in economic structures or the distribution of capabilities, and raises important questions regarding the roles of agency, uncertainty, and ideas in advancing change. In this introduction we examine the role of wars and economic crises as socially constructed openings for change. We attempt three things: to critique materialist approaches in the security and political economy issue areas, to outline the distinctive contribution that an agent-centered constructivist understanding of such events offers, and to offer a framework for the study of such events, one which highlights an expanded range of elite-mass interactions.