Conceptions of nationhood (i.e., who is accepted as a member of the national ingroup) are known to be more open in countries with inclusive citizenship and integration policies. Yet, surprisingly, up to now no research has investigated whether the sharedness of these conceptions is related to national policies. Therefore, relying on data from the 2013 International Social Survey Programme, the present study examined to which extent individuals living in 188 regions of 21 European countries share similar conceptions of who is a “true” member of the nation. Both ethnic (e.g., having national ancestry) and civic (e.g., respecting national laws and institutions) criteria were considered. Multilevel analyses revealed that in countries with more inclusive policies (with inclusive citizenship regimes, and where immigrants are granted more political rights) the average regional importance granted to ethnic criteria was lower, and conceptions were more heterogeneous (i.e., less shared). Civic criteria—that are achievable—were deemed more important. This can explain the lower heterogeneity of civic conceptions of nationhood and the lack of impact of national policies (though the average regional importance of these criteria was higher where immigrants had more rights). Overall, these results suggest that inclusive as opposed to exclusive settings leave more room for differing worldviews.