Since a few years have developed speeches on ‘ethnicity’, ‘assertions of identity’, in French society and in particular in the School. Whether these socio-media speeches are fascinated by what is known as ‘misweaving’ or are afraid of these statements, they constitute a new ‘social problem’, a problem that questions French society and school, and which not only concerns students with a migrant background. Our article is based on the cross-results of two surveys, conducted through lengthy observations and repeated semi-directional interviews. One relates to the ways of building identity that change in the CM2/collège passage (which corresponds to a threshold effect towards adolescence), for students who are identified by teachers as likely to encounter significant difficulties in the remainder of their schooling. It is based on monitoring of sixteen pupils for 2 years, in the neighbourhood, schools, peri-school and prevention associations they attend. The other research focuses on ways of testing identity constructions for colleges in ‘relay facilities’. These two surveys are not disjoined in the draft Communication: all in the school files of colleges of relay facilities suggests that they were schoolchildren comparable to those followed in the first survey. Our aim is therefore to trace processes of identity building on what is happening between the family, school, district copats, social backgrounds and ambient discourse: how can young people who were seemingly “happy” schoolchildren, applied to follow the teaching instructions, become teenagers who ultimately reject the School and all educational institutions because they feel oppressive on ethnicised criteria? colleges who refuse to participate in “Blancs apprenticeships”, dichotomising the pedagogical relationship between “them” and “us”? When and under what conditions does this ethnicised perception of education manifest itself, and with what dependence and independence from ethnicised perceptions of society? Following the presentation, in the first part, of the phenomena as they manifest themselves, the second part of the communication shows how the ethnicisation of the School is fuelled by developments which are hardly perceived by those involved in education as playing a decisive role in this area: * the evolution of social classes and their relationships and the evolution of the way in which they are given in society * by the paradoxical evolution of how school culture is seen (less ‘distinctive’ 4 seemingly, but making it possible to see in a more opaque way the knowledge of legitimate culture as spaces for social conquest) * by changing educational forms and knowledge (individualisation and essentialisation). These developments lead us to show that, contrary to opinions of common sense, ethnicisation is not only a phenomenon that ‘invades’ the School, but that it, through some of its developments, actively contributes to the perception of ethnicism in society.