It is a premise of this book that European integration and EU politics will become more and more politicised. Political parties will, therefore, play a more important role in EU governance. The book envisages the European party system after enlargement, with political parties from the ten new EU member states as new participants and actors in the party arena of the EU. The ten country chapters (authors are experts, most of them from the respective country) deal with the attitudes and activities of political parties towards European integration and the EU (focussing on referendums on EU membership and on the 2004 European elections) and with the affiliations of these parties to the party groups in the European Parliament and the party organizations at European level. The annex informs on parties in the ten new EU member states, on the composition of the political groups in the EP and on the results of the referendums on EU membership and the EP elections in the respective countries. The book is primarily for scholars, students and political practitioners interested in the fields of European integration and EU politics, in political parties and the party system in general and in the ten new EU member countries, in the role and structure of the European Parliament and in the emerging European party system.