This chapter provides a historical overview of the evolution of European cooperation. It first sketches the historical background to several initiatives for international cooperation after the Second World War. It then discusses the way the EU evolved from the initial founding of the European Coal and Steel Community into what is now the European Union. In doing so it looks at the evolution of its policies, institutions and membership over the decades and highlights major international events and crises that affected developments. The chapter shows that the process of bringing the European countries together was long and winding with many fits and starts. Periods of rapid change and innovation have alternated with long stretches of gridlock and stalemate. The process was often erratic because of fundamentally different views on the nature, pace and scope of integration. While the term ‘European Union’ suggests that the organization was swiftly put in place on the basis of a solid design, the EU in essence is a patchwork that has been stitched together in a step-by-step fashion over the course of seven decades.