Students' perception of teachers' mindset beliefs (TMB) is associated with their school engagement (SSE). Based on SSE's contextual-personal interplay, perceived classroom goal structures (CGS) and students' mindset beliefs (SMB) were considered. Data from 1071 high school students were analyzed. The results show that CGS significantly mediated the negative connection between perceived headteachers' fixed mindset beliefs and SSE. Students who perceived headteachers to endorse more fixed mindset beliefs aligned with classroom performance goal structure (PGS) rather than mastery goal structure (MGS) environments, predicted fewer engagements. SMB played a moderated role. The effect of MGS on SSE was much stronger for students with low fixed mindset beliefs, whereas the effect of PGS on SSE was significant only for students with high fixed mindset beliefs. These findings corroborate SSE's development-in-sociocultural-context theory, indicating the value of inculcating growth mindset among teachers, and the fitness of classroom-student motivational systems to improve adolescents' engagement.