Book excerpt: Party systems are crucial elements for the functioning of political systems and representative democracies. With several European countries experiencing significant changes recently, it is necessary to update our knowledge. This volume analyses party system changes in Europe in the 21st century by considering several dimensions such as interparty competition, the cleavage structure, electoral volatility and the emergence of new actors. The book describes the principal continuities and changes in party systems in Europe; analyzes the main explanations for these trends; and assesses the impact of the crisis on the patterns observed. By considering a wide range of Western and Eastern European countries, and focusing on the ‘parameters’ of party system change, this book seeks to fill an important gap in the literature through a comparative analysis of the evolution of party systems in Europe over the last decades. This book will be of key interest to scholars and students of political parties, party systems and politics, electoral behavior as well as more broadly to European politics, comparative politics. political representation and the quality of democracies.