In this book, Christina Zuber outlines a theory of ideational policy stabilization to explain stable policy choices despite changing incentives. Historical legacies are frequently invoked in popular and academic accounts of the politics of migration, but the mechanisms of transmission are left underspecified. This work contributes to research on migration and to theories of public policy by arguing that the missing link between past events and present choices is ideational: initially a historical constellation of interests leads actors to defend policy ideas that match the historical environment, but over time, ideas can detach themselves from interests and stabilize into societal dispositions (shared values and identities). This occurs if elites build a discursive consensus around a policy idea, and if bureaucrats develop concomitant policy practices. The book''s empirical section analyses ideational stabilization in Catalonia (Spain), which takes an inclusive approach to immigration,