This study investigated the relationships between maternal, paternal, teacher, and peer social support, behavioral engagement, and school burnout among Finnish lower secondary student athletes (n = 209) and regular students (n = 156) using cross-sectional questionnaire data collected in Grade 7. Structural equation modeling revealed positive associations between social support and student behavioral engagement, and negative connections between social support and behavioral engagement and school burnout. Behavioral engagement mediated the association between maternal and peer support and school burnout, and teacher support was the strongest direct predictor of school burnout. Student athletes displayed stronger associations between behavioral engagement and school burnout in comparison to regular students. The results contribute to our understanding of the interplay between individual and environmental resources in shaping student athletes' and regular students' well-being in lower secondary school.