This study reviews the transformation of governing structures in Europe over two centuries and examines the structural impact of the European Union (EU) on Turkish politics and polity. The Ottoman elites reformed governing structures during the 19th century and transformed a multinational and multireligious empire into a nation-state with a modern administrative structure similar to European examples. Today the Turkish governing elites are faced with a European challenge on similar terms, but with crucial differences in dimensions and impact. The EU conditions for Turkish membership are of a revolutionary character in that they require fundamental changes in the governing structures of the republican regime. Although Turkey-EU relations are evaluated in terms of EU conditionality, Europeanization poses a tremendous challenge to the nation-state and requires a transformation of basic governing structures and mentalities.