Ethnic boundaries were tested in students' networks in 34 Flemish and 19 Dutch high schools. Each network consisted of a school cohort in an intermediate level of education ( track). While students from the native majority predominantly had friendships within their own ethnic category, minority students often had more inter-ethnic than intra-ethnic friendships. However, a multilevel p(2) model for analysing the networks showed that this was due mainly to the quantitative dominance of native students in the networks. Native students were more inclined than minority students to engage in inter-ethnic friendships. The study found ethnic boundaries to be stronger in the Dutch networks than in the Flemish networks. It is unclear whether this is due to methodological reasons or to more substantial differences between the Netherlands and Flanders.