This book considers the dynamics of institutional conflict and institutional change in international organizations, specifically focusing on the European Union, the most highly integrated international political order on the globe. In a world where political decision making increasingly takes place above the nation state level, it theorises the social mechanisms that lead to the point at which these tensions become explicit and the customary functioning of international political orders tips into outright conflict between different organizational entities. Taking a constructivist approach, it examines two in-depth case studies - in the field of Justice and Home Affairs (JHA) and the EU’s Common Foreign and Security Policy (CFSP) - to explain the dynamics of the processes that lead up to institutional conflicts and provide some explanation for their final outcomes. This text will be of key interest to fields of and European Integration, EU Politics and more broadly International Relations.