The effect of policy regimes on immigrant incorporation has been the subject of extensive debate. Despite much theoretical literature on the subject, the relationships between specific national policies in various domains and outcomes broadly related to social solidarity have not been well explored empirically. The present work develops measures tapping the priority of “ascriptive” traits defining membership in the national community. It tests the expectations of the theoretical literature on multiculturalism, citizenship policy, and social welfare redistribution against these measures across 18 immigrant-receiving democracies. Cross-sectional analyses on, 2003 data indicate that both jus soli citizenship regimes and high levels of social spending are related to more immigrant-inclusive definitions of the national community, but the effect of multiculturalism is inconsistent. Examined longitudinally, the effect of a jus soli citizenship regime and social spending remains consistent, but citizens in multicultural countries appear to have become substantially more “ascriptive” on these outcomes over time.