Post-2008 developments in European politics have reopened the debate on the extent to which we are witnessing a fundamental transformation of patterns of party competition and protest mobilization. Two phenomena in particular have drawn attention: the success of new parties and the rise of movement-like mobilization. Despite the attention devoted to them, it is unclear whether these developments have transformed the underlying programmatic structure and patterns of mobilization in European societies. Therefore, the dissertation examines the structure of political conflict in countries from northwestern, southern and eastern Europe, from the perspective of: (1) party system stability and; (2) the interaction between electoral and protest mobilization. The article-based dissertation is composed of four chapters, each with a separate empirical analysis of one aspect of the over-arching theme of the changing structure of political conflict. The first two empirical chapters examine party system stability by distinguishing between the programmatic and organizational dimensions. The first examines the interaction between the programmatic and the organizational dimensions of party system stability through a comparative analysis of fifteen European democracies across the three regions. The chapter presents four ideal-typical scenarios: stable systems, instability, systems with ephemeral parties and systems with empty party labels. The second empirical chapter offers a case study of party competition in Romania, to show the role played by political issues centred on reforming democracy and fighting corruption in maintaining programmatic instability and helping mainstream parties survive. Both chapters rely on similar methods and are based on ‘core sentence analysis’ of issue salience and party positions as presented by two national newspapers. The third and the fourth chapters challenge the conventional approach of examining electoral competition as a self-contained arena of mobilization. Both chapters provide a comparative analysis of political conflict in light of the interaction between the electoral and the protest arena. The third chapter focuses on party sponsored protests and presents the type of parties which most frequently rely on protest mobilization. The chapter relies on an original large-n protest event dataset collected by the POLCON project across 30 European democracies, a subset of which contains events linked to political parties. The chapter shows that the typical protest party is: in opposition; ideologically on the economic left and cultural right; belongs to a radical party family and; has a mass-party organization. Protest parties are shown to be mostly present in new democracies and thrive in the context of a weak civil society. The fourth empirical chapter examines the interaction between the two arenas from the perspective of protest participation. Based on individual-level data from the European Social Survey and hierarchical logit models, the chapter shows that unlike in countries from northwestern and southern Europe, in eastern European countries right-wing citizens are more likely to protest than their left-wing counterparts. This ideological difference is explained by regime access, both historically and in the present. The chapter finds that partisanship and government ideology contribute to differences in the composition of protest.