This article provides an overview of the study of the European Union since the doldrums of the 1970s. We focus on three debates that have helped to shape the field. Has European integration centralised state control or is European integration part of a process of dispersion of authority? What is the role of identity in framing preferences over European integration? And, finally, is European integration part of a new political cleavage? We observe that the European Union is a moving target. It has a habit of throwing up new and unexpected facts which wrong-foot extant theories. We have no grounds for believing that this will not continue.