According to Bronfenbrenner's socio-ecological model, school is an essential microsystem of the developing child. Schools provide important developmental contexts for children and adolescents, as they constitute environments that might either foster or evoke students' emotional instability. In particular, less is known about the precise and dynamic interplay of students' socioenvironmental aspects in school (i.e., sense of school belonging, social relationships with teachers and peers) and emotional instability (i.e., depressive symptoms, perceived stress, feelings of loneliness) during adolescence. To close this gap, this study examined within- and over-time cross-lagged associations based on data from a quantitative questionnaire-based survey of adolescent students (T1: N= 1088; Mage = 13.70, SD = 0.53) from 23 secondary schools in Brandenburg, Germany. Results of latent cross-lagged panel design supports the mutual relations for within-time associations, which is in line with Bronfenbrenner's model. However, only the over-time association between school belonging and teacher-student relationship was found to be reciprocal.