Intervention in party settings lies at the intersection of prevention, early detection, and care, including risk and harm reduction. In Besançon, a collective provides prevention services—listening, information, and support—at all types of festive gatherings, primarily attended by young people. There is much to learn from this type of intervention, which operates on the ground without judgment or coercion. Among other things, the initiative includes a recovery room for people in distress following substance use.