Few political phenomena in political science have been mapped and measured as extensively as party systems, yet many of the existing frameworks for measuring and explaining the extent of their stability and change have increasingly been found to be wanting. This panel brings together scholars from both sides of the Atlantic, with a blend of expertise spanning not just Western, Central and Eastern Europe, but also the generations. The contributions provide a variety of perspectives of how to measure and explain the dynamics of European party systems. Three papers tackle questions of measurement. Deegan-Krause et al. contend that new patterns of party system change are affecting political systems in ways that we are only now beginning to understand, but the speed of change actually inhibits our understanding because it also disrupts the very measures we use to look at party system change. Therefore, the paper proposes new techniques and comprehensive concepts to better measure and understand the nature of changes within party systems and illustrates the phenomenon by drawing on data from the Political Year Databook which Deegan-Krause edits. Taking data from Central and Eastern Europe in their respective papers Kreuzer & Pettai and Ghergina explore two central aspects of measurement. Kreuzer & Pettai focus on party age highlighting that efforts to capture a party system’s age have been limited to report the age of its major political parties. Their paper proposes a new more systematic measure of a party system’s age that is based on the organizational continuity of political parties. Ghergina’s focuses on some of the drawbacks of the much used volatility measures, demonstrating the merits of investigating the relationship between gross and net electoral volatility. Recognizing that full explanations for the motors and mechanisms of party change also need to pay close attention to particular cases, the final two papers explore particular countries. Pappas examines the earthquake Greek elections of 2012 focusing in particular on the specific mechanism that made the two party system durable and when state related resources became scarce, also caused its breakup. Haughton examines the patterns of party politics in Slovakia highlighting the limitations of many of the existing frameworks for explaining party politics such as legacies, the exit from communism, institutions, EU accession and cleavages. He suggests that other explanations rooted in an understanding of the politics of independence, the depth of party organization and the shelf-life of appeals are key to the answer of what causes stability and change in party systems.