The book extends research on the territorial structure of party systems (party nationalization) to 20 post-communist democracies. It explains party nationalisation as a consequence of ethnically oriented politics, and shows how party nationalisation can increase our understanding of electoral systems.Introduction: Electoral Systems and Party Systems in the New European Democracies The Puzzle of Electoral Systems Impact in Post-communist Democracies How to Measure Party Nationalization Explaining the Nationalization of Party Systems in Central and Eastern Europe How Party Systems Develop in Mixed Electoral Systems Counting Votes and Places: The Joint Effect of Electoral Rules and Territory Conclusion: An Institutional Model to Predict the Number of Parties in Central and Eastern EuropeDANIEL BOCHSLER is a Research Fellow at the Central European University, Hungary. He studies comparative politics, with a particular emphasis on the nationalization of party systems and on electoral systems. His work has been published in Electoral Studies, Public Choice, Regional and Federal Studies, and the Swiss Political Science Review.