The topic of this book is political cleavages in 19 countries in Central and Eastern Europe. The theoretical link between political stability and political cleavages is simple – the emergence of a stable party system and distinguishable and consistent voter preferences are typically seen as indicators of democratic consolidation (cf. Whitefield 2002; Krause 2004; Berglund and Ekman 2010). However, the topic of this volume is not just the consolidation of democracy in a post-communist setting, since the analysis will cover everything from full democracies to hybrid regimes and more or less authoritarian political regimes. The idea is rather to discuss the emergence of political cleavages and their consequences for political stability – in terms of regime continuity – in the eastern part of Europe. The analysis will thus not only add to our understanding about contemporary party–voter linkages in a post-communist setting, but also to our knowledge about regime dynamics in a region characterised by political diversity.