Book excerpt: European integration is in a time of multiple crises, which has a profound impact on different EU policies. This book presents a major collaborative research project uniting international colleagues in the quest for developing a theory: when and how will crisis induce policy breakthrough as opposed to stalemate? In this volume, a team of renowned authors compare the effects of the recent financial, economic and neighbourhood crises on the EU's main policy domains, including financial market integration, trade, health, migration, research, energy, foreign and state aid policies. This book was originally published as a special issue of the Journal of European Integration.