The latest crises in Europe—the Euro crisis and the migration crisis—have both led to massive domestic political conflict and mobilization. From a cleavage perspective, it is important that the various contested issues, such as European integration and immigration, have not been articulated in isolation. By contrast, political actors have linked them to one another and often to a broader—usually populist—criticism of representative democracy. The project takes such issue linkages as its starting point and asks the following questions: How do challengers link issues? What are the consequences of different types of issue linkages for politicization in public debates and for the capacity to mobilize support? The research design combines (i) a comparative study of contentious episodes with (ii) focused experimental surveys. The former develops tools to measure issue linkages and their effects on public debates, the latter allow to link the supply of issue linkages with individual-level responses.