Background/Context: The article presents the outcomes of international comparative anthropological (qualitative) research on multiculturalism, citizenship, and nation building in schools in Paris, Berlin, London, and Rotterdam. The findings presented here are based on fieldwork carried out over a period of 1 year at secondary schools in the Dutch city of Rotterdam and in London. The project has demonstrated a close relationship between national specific modes and trajectories of integration and the ways in which the schools deal with diversity. Purpose/Objective/Research Question/Focus of Study: This article addresses the growing diversity in religious and ethnic backgrounds among students at primary and secondary schools in Western Europe. The debate about the place of religion in school has gained momentum after the arrival of large numbers of migrants, especially those with a "new" religious background, such as Islam. Their presence challenges existing arrangements and privileges and puts matters that were previously taken for granted back on the agenda. Religion and ethnicity at school touch on a fundamental issue, namely the place of state schooling in the making of modern nation-states. Several issues need to be taken into account: To what extent is religion a legitimate moral resource? Why should one learn about religion, and who should teach it to whom? Is it more important to get religious nurturing or to study the plurality of different belief systems? Should the school accommodate religious and cultural diversity, or should it rather be a neutral arena that deliberately disregards this diversity? These questions do not arise together in one package but present themselves in fragmented, occasional, and contingent ways. Setting: The data were collected during intensive ethnographic fieldwork in four secondary schools in Neukoln (Berlin), Saint Denis (Paris), Crooswijk (Rotterdam), and Haringey (London). Research Design: Qualitative fieldwork, case study in secondary schools. Conclusions/Recommendations: The outcomes of the study demonstrate that although schools are, to a large extent, unique settings that cannot be lumped together, they are crucial sites where principles of national civil incorporation are transmitted to pupils. Although the two schools described in this article resemble each other to a large degree in terms of ethnic composition of the neighborhood, problems faced, and policies adopted by the school board, they each have their specific way of dealing with ethnic and religious diversity. These ways reflect national specific political culture in each of the two countries.