This book investigates the structural and political implications of the European Union's eastward expansion and the subsequent necessity of redefining its institutional boundaries. Jan Zielonka, a professor of European politics, utilizes historical analysis and institutional theory to argue that the traditional model of a centralized, monolithic European state is increasingly incompatible with the realities of a diverse, enlarged union. He proposes a shift toward a more flexible, multi-layered governance model that accommodates varying levels of integration among member states.

Scholars and political analysts frequently cite this work as a critical contribution to the debate on European integration and the limits of institutional expansion. Readers often note the academic density of the prose, which is tailored for students and professionals in the field of international relations.