Résumé : Purpose: The current study investigated the association between body mass index (BMI) and health-related quality of life (HRQoL) among a large and non-clinical sample of adolescents, and tested the possible moderating effect of perceived teacher and classmate support on this association.Methods: French-speaking Belgian adolescents (n=11,342) self-reported height and weight, HRQoL (KIDSCREEN-10), as well as their perception of teacher and classmate relationships. Adjusting for sociodemographics, linear regression analyses with HRQoL as the outcome variable were performed for boys and girls separately. Interactions between BMI and teacher support, and between BMI and classmate support were included to examine the effect of this support on the association between BMI and HRQoL.Results: Obesity was associated with lower HRQoL for boys (β = -2.14, p=0.002) and for girls (β = -2.96, p=0.001), while only overweight girls showed a significant impaired HRQoL compared with normal-weight ones (β = -0.94, p=0.01). In both sexes, lower perceived teacher and classmate support was associated with lower HRQoL. Interactions between BMI and perceived teacher relationships, and between BMI and perceived classmate relationships were not significant for boys as for girls.Conclusions: Perceived school-related social support constitutes an important dimension of adolescent well-being, suggesting the relevance of considering it for promoting greater HRQoL in overweight and obese youth. Future studies are needed to confirm the absence of moderating effect of this support and explore its effect on other weight-related factors, like body image, weight misperception and bullying, associated with decreased HRQoL in adolescents.