In France, as in many countries, the impact of socioeconomic inequalities on individuals’ health is evident from a very young age. The proportion of middle school students who report being in excellent health is higher among those from advantaged socioeconomic backgrounds (41%) than among those from disadvantaged backgrounds (34%). These inequalities are particularly pronounced in the areas of diet and physical activity, especially when considering reports of engaging in sports for at least two hours per week, which are significantly higher among the most advantaged students (60.9% vs. 33.5%). Obesity and overweight are more prevalent among the least privileged students than among the most privileged (18% vs. 8%). The effect of social inequalities is reversed when it comes to psychoactive substances: experimentation with cannabis during adolescence is more common in advantaged environments (15% of students have used it at some point in their lives vs. 9% among the least advantaged).