Studies about drug use and drug sale have mainly analyzed the trajectories of marginalized individuals, in precarious situations, living in disadvantaged areas and with a migratory background. The samples of these researches are a reflection of populations arrested for drug sale or drug use by the police or who frequent harm reduction and addiction structures. However, most drug uses and drug sales are carried out by socially integrated individuals, but social sciences are much less interested in this unmarked majority group than in the minority group of the marginalized. The purpose of this communication is to identify the theoretical, methodological and practical issues of research on an unmarked group with illicit practices. This communication is based on the data collected during my thesis in sociology, which studies trajectories of socially included women in the drug worlds. 65 interviews were conducted with persons who use or sell drugs (35 women and 20 men) in Bordeaux (France) and Montreal (Canada). The first issue of this research with an unmarked group is theoretical, and consists in legitimate research in a field where analysis is often a premise for intervention. The second challenge is methodological, and consists in reaching a population of persons who use or sell drugs seeking at all costs to move away from the social representation associated with their illicit practices.The last issue, more practical, is about questioning the position of a researcher in an interview situation with an unmarked group seeking to highlight their social normality to avoid being « labeled » as deviant. Studying unmarked groups implies to analyze the way social sciences can contribute, likely in spite of themselves, to define the categories targeted by social control.< Réduire