This chapter focuses on the historical development of the European Union. The history of the EU began when European governments responded to a series of domestic, regional, and global challenges after the Second World War by establishing new transnational institutions in order to accelerate political and economic integration. These challenges ranged from post-war reconstruction to the Cold War, and then to globalization. Driven largely by mutually compatible national interests, Franco-German bargains, and American influence, politicians responded by establishing the European Communities in the 1950s and the EU in the 1990s. The chapter examines the Schuman Plan, the European Defence Community, the European Community, the Economic and Monetary Union (EMU), enlargement, constitution building, and the Eurozone crisis.