--- - |2 We investigated the development of school and sport burnout in adolescent student‐athletes (N Time 1 = 391, N Time 2 = 373) during their first year in upper secondary school using an embedded mixed‐methods design. The questionnaire‐based data were analyzed with growth mixture modeling and four burnout profiles were identified among student‐athletes. From the found burnout profiles, two were typical for the interviewed subsample of elite athletes (n = 17), that is, burnout risk and non risk profiles. We generated rich descriptions of well‐being and ill‐being, showing that elite athletes in two burnout profiles differed in their experienced demands and resources related to individual and environmental factors. The results can be used to generate practical tools for burnout detection in student‐athletes’ educational path. - Journal of Research on Adolescence, EarlyView.