The establishment of Banking Union represents a major development in European economic governance and European integration history more generally. Banking Union is also significant because not all European Union (EU) member states have joined it, which has increased the trend towards differentiated integration in the EU, posing a major challenge to the EU as a whole and to the opt-out countries. This book is informed by two main empirical questions. Why was Banking Union—presented by proponents as a crucial move to ‘complete’ Economic and Monetary Union (EMU)—proposed only in 2012, over twenty years after the adoption of the Maastricht Treaty? Why has a certain design for Banking Union been agreed and some elements of this design prioritize...