The euro crisis made Europe’s stateless currency falter. This book retraces and interprets the ways in which the crisis impacted the unique institutional set-up of Europe’s Economic and Monetary Union (EMU). It argues that the crisis propelled the European continent towards the institutionalization of an unprecedented form of centralized authority: Europe’s New Fiscal Union. Diving into the central functions of fiscal surveillance, financial assistance, lending of last resort and banking resolution, the book reveals how a covert and convoluted mutualisation process occurred in the shadow of the euro crisis management. Based on 62 interviews conducted by the author with senior policy-makers in Brussels, Frankfurt, Helsinki and Rome, the book claims that Europe’s New Fiscal Union is largely unsettled and still unstable. It therefore engages with the challenges arising from the patchwork of newly adopted rules, instruments and bodies, suggesting crucial reform steps to make EMU sustainable.