What are the driving forces and consequences of the politicization of immigration issues in European democracies? Immigration has been one of the key issues responsible for the emergence of a new “demarcation-integration” cleavage in Western Europe. While there is evidence that the radical populist right has been a driving force of this transformation, the political strategies, mechanisms and dynamics of this re-structuring of political conflict are still not sufficiently explored. By using the concept of politicization, the project aims at exploring the parties, party strategies and party constellations responsible for a politicization of immigration issues across political arenas. Moreover, the project will analyze the link between politicization and immigration policies systematically. Does politicization necessarily lead to more restrictive immigration policies? Or can we identify party constellations and electoral strategies which allow liberal immigration policies without fueling radical populist mobilization?