The rekindling of the European Union enlargement talks and Brexit require a reappraisal of the law of the EU's proximity policies. In that light, this book turns Wider Europe into an analytical concept to capture the legal and political facets of the extension of the EU's legal space in the Union's neighbourhood. The book follows three lines of inquiry. Firstly, it reflects on the similarities and differences between internal and external integration, drawing a distinction between EU membership law and EU neighbourhood law. Secondly, it unravels the techniques for the extension of the EU's legal space across different partnerships in the Union's neighbourhood. Thirdly, it sheds light on the political covenants underlying the variety of institutional arrangements of the extended EU's legal space.The book discusses how EU neighbourhood law entails a reconfiguration of how sovereignty is exercised both in the EU and in third countries participating in the Wider Europe.