Theory of Mind (ToM), a central feature of social cognition, impacts social functioning and academic competencies. Yet, the interplay of ToM and self-concept in academic context remains unknown. This study examines how ToM shapes adolescents' academic self-concept and its association with academic competence, while considering the role of gender in these dynamics. The results show that 12-year-olds' academic self-concept aligns with their parents' perceptions of their academic competence for girls and boys. ToM relates to academic self-concept specifically for girls. Moreover, academic self-concept mediates the associations between ToM and academic competence in girls. Explorative analyses on the role of family context for ToM showed no association between the number of siblings and ToM. These results support constructivist theories that suggest that self and mind development are rooted in interpersonal experiences within a social context. This study enhances a nuanced understanding of the link between social cognition and academic achievement in adolescence, highlighting gender differences in these processes.