This volume aims to contribute to the analysis of the EU in general and the background and consequences of its 2004 enlargement in particular. This enlargement is by far one of the greatest tests for the European Union and its institutions because the process of Europeanization is taking place in a variety of countries with diverse political cultures and dissimilar perceptions about the meaning and commitment to European integration. Given their differences in political and economic power, incumbent and new members are inevitably altering the functioning and character of the EU, a unique polity in the international system. Derived from this theoretical challenge, the chapters of this book suggest some explanations on six areas related to th...