[Introduction: Healthy behaviours become less common when descending the social ladder, which contributes to social inequalities in health. General practitioners (GPs) could have an impact on this general trend by providing preventive care counselling. We wanted to describe the social inequalities related to physical activity (PA) and the counselling given to patients, in order to improve our understanding of how inequalities can be produced at the doctor-patient relationship level.Methods: Prev Quanti simultaneously examined social differences in the patients’ level of PA and in the PA counselling provided by their GPs. 3,640 registered patients were randomly selected from the patient list of 52 GPs involved in GP training in two Parisian Universities. Based on interviews with 99 GPs from the same area on preventive care, Prev Quali explored the construction of the GP’s PA counselling practice style.Results: A social gradient was observed, with less counselling at the bottom of the social ladder, where lower levels of PA were also reported by patients. Interviews revealed a common difficulty for GPs to consider PA as a valuable form of medical care and the lack of a systematic approach. An implicit triage process leads to an indirect social selection of the patients “worth trying” to deliver PA counselling, by GPs barely aware of the social gradient among their patients in terms of PA.Conclusion].