This book explores the question of how the EU understands the ‘rule of law’ in its external relations, with a particular focus on development cooperation and enlargement. Although the EU’s commitment to the rule of law is strong, the relevant concept remains nebulous. On the basis of a detailed analysis of two key EU external policy areas, the main argument advanced is that the Union has adopted a mostly ‘institutional’ approach to the concept by focussing largely on judicial reform. By testing the relevant practice against the background of the constitutional traditions of the Member States and legal theory, the book attests to the significance of developing a comprehensive approach to the rule of law in EU external relations.