EU internal security concerns such as migration, police and judicial cooperation are today part of EU foreign policy. This book shows how those concerns have taken over the EU agenda towards Mediterranean countries. Adopting a rational-choice institutionalist approach, it explores EU policy in the region since the turn of this century. Findings provide clues on how to re-design EU policies towards the region following the 2011 Arab revolts. Investigating the cases of border management, counter-terrorism and rule of law promotion through the lens of a rational-choice-historical institutionalism, the book contends that the development of a Justice and Home Affairs (JHA) Mediterranean dimension was contingent upon two independent variables: states' preferences and historical legacies. Contrary to the expected outcome, which would be that the various decision-making rules constrained the actors, the sense that emerges is that the development of a JHA external dimension depends on the intended strategic action of actors and is affected by time.