The object of this research is to account for the uprising of ethnic categories in french society. Its specific purpose is to restitute the uses of these categories : under which circumstances and context are they called up in order to read various situations and organize human social interactions ?<br />Such an object takes place within the general ethnicity question, centred on the categorical ascription and social interaction processes. The challenge is to know how are produced, labelled and crystallised the boundaries between "They" and "Us" and what are their effects on the behavior of people involved in the personal interactions where this dichotomy is relevant.<br />In this work we focus on the link between the social acknowledgement...