What makes some multiethnic states integrate and others descend into civil war? Ishiyama and Breuning extend traditional explanations centred on socioeconomic, cultural and historical factors to argue that the actions of leaders of ethnic segments - too often ignored - are also critical determinants of policy outcomes. Applying a framework derived from comparative politics and IR theory, the authors explore two sets of empirical cases: the emergence of new nationalisms in old European democracies (the United Kingdom and Belgium), and the re-emergence of old nationalisms in several new democracies (the Baltic states, Moldova, Czechoslovakia and Yugoslavia).