Are there generational differences in ethnic and religious attachment among Muslim minorities in the Netherlands? To answer this question, we assess patterns of ethnic and religious identity and practice as well as their interrelation among Dutch Turks and Moroccans. Classical assimilation theories predict a decline in ethnic attachment over generations, but are less clear on consequences of migration on religious attachment. We use quantitative analysis to test propositions among first and second generation minorities (N1,861). Our data indicate that the second generation reports weaker ethnic and religious identities, and engages less in ethno-cultural and religious practices. We do find, however, that religious and ethnic identity become increasingly related for the second generation. These differences can only partly be accounted for by differences in education, employment and life course events.