This article investigates differences in the composition of Flemish pupil groups with regards to ‘risk characteristics’ that promote ethnocentric attitudes. Pupil groups are compared on a broad range of social, economic and cultural characteristics and these aggregated group characteristics are transformed into one measure which reflects the presence of pupils that share risk characteristics promoting ethnocentrism. Differences between the groups are considerable, especially those between the educational tracks. A strong presence of pupils sharing ethnocentric risk characteristics has an independent effect on pupils’ attitudes towards immigrants. Within groups with a high degree of ethnocentric risk characteristics, pupils report more negative attitudes towards immigrants than within groups with fewer of those characteristics, and this regardless of their own individual characteristics. Autochthonous students from ethnically-mixed pupil groups also report less negative attitudes towards immigrants than autochthonous pupils from groups with a high degree of ethnic homogeneity.