This article focuses on the impact of measuring quality in family medicine. Throwing the reforms that have affected private practice into temporal perspective shows that it has recently undergone a decisive “metric-oriented turn”. Effects of quantitative assessment on general practitioners are observed thanks to two original studies on preventive care. Professionals’ critiques and forms of resistance are examined before delving into the experiences and arguments of GPs who consent to the measurement of medical work, even agreeing to do it themselves. We end by evaluating the ongoing inflections of the professional model and the way the private medical sector in France is governed.