Ethnic minorities in Europe show diverging patterns of educational success, but in most national contexts, migrants and children of immigrants have lower achievements in terms of grades than their majority peers. This study asks whether social exclusion in the classroom can contribute to explaining this pattern. While limited access to social resources is often assumed to be of significance for educational success, it has rarely been measured explicitly. In this study, social exclusion is measured accurately and on alarge, cross-national scale, by usingsocial network data from 731 classrooms in England, Germany, and Sweden (CILS4EUdata). Results show that social exclusion is negatively associated with school grades, but this does not contribute much to understanding grade differences between children of immigrant and children of majority background.