The analysis of party systems has moved from the studies of typologies or classification schemes to the focus on how and why party system features change. This chapter reviews the main approaches used in the study of party system change and examines the main findings for European countries over the last decades. The study also conceptualizes the European crisis as an exogenous (economic and political) shock that may affect the transformation of national party systems. This allows us to elaborate the theoretical framework used to analyze the impact of the Great Recession on party systems. Finally, the chapter presents four scenarios of the transformation of party systems and argues that the European crisis may unveil its effects through distinct mechanisms, leading to different trajectories of party system change.