On 1 May 2004 at a historic, if understated, signing ceremony in Dublin the European Union (EU) formally recognized the accession to the Union of ten new states. These were the Mediterranean ‘micro’ states of Cyprus and Malta, and eight new members from Central and Eastern Europe(CEE) –the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, and Slovenia – which, for more than fifty years, had been cut off from the European integration process by virtue of their geopolitical imprisonment behind the Iron Curtain. The eastern enlargement was completed via the ‘coda enlargement’, with the accessions of Bulgaria and Romania in 2007. At that point the EU completed its extraordinary and cumulative geographic sweep: the first enlargement in 1973 was ‘west’ (UK, Ireland and Denmark), the emphasis in the 1980s was on the ‘south’ (Spain, Portugal and Greece); in the 1990s the Union expanded ‘north’ (Finland, Sweden and Austria). The history of European integration has been one of successive and successful enlargement rounds; ‘widening’ has proved as potent a force as ‘deepening’ in determining how the European Union has evolved as a post-national inter-state and supra-state zone of peace and relative prosperity. For more than three decades after World War Two, the Cold War stood in the way of the realization of the oft-stated ambition to unite ‘east’ and ‘west’ in a single European constellation of states. But with the demise of the Soviet Union and the loosening of its post- War grip on its Central and Eastern European satellite states in the wake of 1989’s so-called ‘geopolitical earthquake’, Jean Monnet’s ambition of a European construction stretching from the Atlantic to the Urals suddenly seemed possible. Thereafter, enlargement quickly made its way to the top of the European Union’s political agenda. Two decades later the EU has applied the successful model of ‘Europeanization East’ in negotiating with states in the Western Balkans and Turkey, though with less than successful results to date. Thus a process which was instituted in the aftermath of the dramatic events that defined the 1989 revolutions and had brought the EU population up to 500 million people now sought to consolidate democracy and European integration in Europe’s most fragile and contested political space. This chapter analyzes the European Union’s enlargement process in the two decades that followed the ‘annus mirabilis’ of 1989. The 1989 Revolutions opened up the possibility of a vast and voluntary framework of economic and political integration extending to a genuinely pan-European scale. At the centre of this historic project the European Union initially demonstrated great hesitation in response to what Jacques Delors termed the ‘acceleration of history’, but gradually found its stride as the European Commission assumed responsibility for the practical implementation of, if not a utopian ‘Return to Europe’ by ‘Yalta Europe’, then a process whereby gradual ‘catchup’ could be pursued and adaptation of CEE states to existing legal and procedural norms of the European Union could be achieved.