Public concerns over the possible effects of school segregation on immigrant and ethnic majority religiosity have been on the rise over the last few years. In this paper we focus on (1) the association between ethnic school composition and religious salience, (2) intergenerational differences in religious salience and (3) the role of ethnic school composition for intergenerational differences in religious salience. We perform analyses on religious salience, one five-point Likert scale item measuring religious salience among 3,612 16-year-old pupils in Belgian secondary schools. National origin was used as a proxy for ethnicity. Ethnic minority pupils in schools with a higher share of ethnic minorities tend to be more religious. This relation holds for Muslim as well as other religious and ethnic minorities. Ethnic school composition also moderates the relationship between migrant generation and religious salience: second generation migrants tend to be more religious in ethnic minority dominated schools. For ethnic Belgians the association is moderated by their religious affiliation: Catholics tend to be more religious, while non-affiliated ethnic Belgians are less religious in schools with a higher share of ethnic minority pupils.