This thesis is a collection of five empirical studies that analyze political competition on immigration and democracy in Europe. The thesis investigates how policy issues related to these two policy domains become politicized, both in terms of citizens’ attitudes and in terms of party competition. The thesis contributes to the investigation of the driving forces of competition on cultural and political issues. The first two chapters of the thesis analyze the dynamics of attitudinal change among citizens by asking (i) how Eastern Europeans’ conceptions of democracy have changed since the transition to democracy and (ii) how short-term exposure to refugees influences attitudes and voting behavior. The following two chapters focus on party competition and investigate (iii) to what extent and why parties politicize democratic systems in their election campaigns, and (iv) how the refugee crisis allowed radical right parties to increase the politicization of the immigration issue. Finally, a comparative chapter adds to the previous chapters by studying (v) how the discourse on immigration and democracy of established parties changes when they are challenged by a new competitor. To show the trajectory of competition on immigration and democratic systems, the thesis draws on a wide range of empirical evidence stemming from Eastern, North-Western and Southern Europe. To detail the parties’ emphasis and positions on issues on a monthly basis, it leverages a novel dataset of 120,000 party press releases. In addition to quantitative text analysis techniques – including structural topic models and wordscores – the thesis relies on classical content analysis and on the analysis of surveys and election outcomes. The empirical analyses reveal two different dynamics of politicization of policy issues: While attitudes and party mobilization on democracy-related issues follow long-term trends, recent change to political conflict related to immigration was shaped by the context of the refugee crisis.