Addressing worldwide declines in adolescents’ school belonging requires identifying factors to target in reversing this trend. We hypothesized that adolescents with higher levels of teacher connection and perspective-taking would have greater school belonging and that the joint association of both factors with school belonging would be more than additive. We analysed cross-sectional survey data from 15-year-olds in 62 countries (N = 392,096) collected in the 2018 Programme for International Student Assessment. Measures were expressed in standard deviation (SD) units. Based on regression models with both factors plus covariates, school belonging increased 0.12 (95% CI: 0.11, 0.13) units for a 1.00 SD increase in teacher connection and 0.09 units (95% CI: 0.08, 0.10) for a 1.00 SD increase in perspective-taking. The observed (joint) association of both factors with school belonging was 19.0% greater than the expected (additive) association. Efforts to increase teacher connection and perspective-taking could improve school belonging.