The Social Differentiation of Children Wilfried LIGNIER, Cedric LOMBA and Nicolas RENAHY The social sciences are not the "usual" sciences of childhood, compared with clinical, or medical sciences. But they can be very fruitful in the study of children, particularly for their invitation to regard childhood as an historical identity, as a critical moment of socialization, and as a differentiated social reality. We insist here on the last perspective, knowing that it is fully compatible with the two others - a differentiated historicization and socialization of childhood may be considered. According to us, the social differentiation of children can be analyzed in at least three directions: the "concrete" differentiation of childhoods, the differential identification of children, the childish perception of social differences. We also point out several methodological problems especially linked with the research on children.