This book examines how the European left reacted to the economic crisis triggered by the banking collapses of 2008, and this first chapter outlines the structure of the book as a comparative analysis across ten EU member states, as well as across the different party families of the left, from social democracy through green left to the radical left. The basic features of the economic crisis that hit the global economy in 2008 are introduced, and the very particular implications it had for the European Union. The chapter then examines how the crisis created a challenge for left-wing parties in Europe, setting out the political ideas linked to the economic crisis.