There is a lack of research examining how students' emotion regulation is linked to their well-being at school. To address this gap in the current literature, we examined reciprocal relations between two important emotion regulation strategies (cognitive reappraisal and expressive suppression) and school-related well-being over 12 months across 2 school years. We collected data from 2,365 secondary and upper secondary students in England (aged 11-19 years) across three waves. Juxtaposing between-persons and within-person perspectives, we used a tripartite (three-part) latent cross-lagged panel model (CLPM), and a tripartite latent random intercept-cross-lagged panel model (RI-CLPM) to examine the directional ordering of the two strategies and well-being over time. Both the CLPM and RI-CLPM showed that reappraisal and school-related well-being were reciprocally related. Reappraisal positively predicted school-related well-being, and school-related well-being positively predicted reappraisal. Reappraisal also negatively predicted subsequent suppression, but not vice versa. Suppression and school-related well-being were not linked. Findings inform the design of intervention research in schools and colleges by highlighting the importance of cognitive reappraisal in the school-related well-being of adolescents.