In response to growing demographic diversity, European countries have selectively implemented political multiculturalism, a set of policies that seek to redefine prevailing conceptions of national identity. We explore the consequences of such policies for mass political support. Applying multi-level modeling to the 2002 and 2010 waves of the European Social Survey and analyzing multiple dependent variables including trust in regime institutions and assessments of the government of the day and the political system’s performance, we show that the extensive adoption of multicultural policies magnifies the degree to which hostility to immigration is negatively associated with political support. This finding, robust to multiple specifications, is corroborated using European Values Survey data. It underscores how policies that challenge citizens’ conceptions of national identity strengthen the link between opposition to immigration and political discontent, furnishing ongoing opportunities for rightist fringe parties to capitalize on anti-immigrant sentiment among the politically alienated.