This study examines to what extent adolescents’ place of residence is related to the opportunities and the preferences to befriend same-ethnic classmates. Analyzing 3345 students within 158 German and Dutch school classes, we find that sharing a neighborhood provides additional meeting opportunities to become friends in class as adolescents are likely to befriend classmates who live nearby them or who live nearby a friend of them (propinquity mechanism). However, this hardly explains why adolescent friendship networks in school classes tend to be ethnically homogeneous. Also, we find no convincing evidence that an adolescent's preference for same-ethnic friends in class varies with the share of outgroup members in his/her neighborhood (exposure mechanism).