This chapter acts as an introduction to the whole volume. It first defines the concept of constitutional imaginary and sets it in the wider context of political theory and philosophy. Next, it explains what is missing from a number of recent publications that deal with European constitutionalism at a more reflexive and theoretical level and how the approach taken in this volume can enrich our understanding of the EU’s present predicament. Two perspectives are particularly important: that of history and that of political economy. The conclusion presents the broader project of which this volume is part and gives a brief overview of each chapter’s contents.