The book is divided into six parts: the first concerns the institutional and legal framework and includes three essays: the genesis of the external dimension of the AFSJ; the Institutional setting and the legal toolkit; a legal perspective of the main problems of the EU external action in the JHA domain. The second part includes three studies; the first is on the principle exclusive competence as applied to the readmission agreements; the second concerns the interaction between the external dimension of the AFSJ and other EU Policies, such as the development cooperation and the common foreign and security policies. The third essay focuses on the Mediterranean dimension of the Area of Freedom, Security and Justice. The third part of the book concerns the sector of migration law, which is one of the subject matters of the AFSJ: attention is devoted to readmission agreements and to the problems of externalization of migration policy. The fourth part of the book revolves around international cooperation and in particular the case of counter-terrorism measures. This part is well connected to the second deliverable of the research project. Three essays cover this issue: the first concerns the EU-US cooperation in the justice and home affairs domain; the second is a broad study of the EU bilateral and multilateral cooperation agreements in the concerned area and the third essay covers considers the EU role as an actor in the global security arena. The fifth part of the book deals with civil and criminal cooperation. It encompasses three studies: the first concerns the EU’s Contribution to Private International Law; the second discusses about new ways of sharing competence between the EU institutions and the Member States in the area of civil cooperation. The third contribution considers the European Union and the implementation of international norms in criminal matters. The final section draws the overall conclusions of the book and addresses the role of the EU as an international actor in the JHA domain: potential, progress and limitations.