This longitudinal study of 1,066 Finnish students examined bidirectional reciprocal relationships between changes in perceived supportive school climate and changes in self-reported truancy from the last year of primary school (Grade 6) to the last year of lower secondary school (Grade 9). The results of the random intercept cross-lagged panel model showed, first, that a decrease in positive perceptions of school climate at the previous time point predicted more self-reported truancy at the following time point. Second, an increase in self-reported truancy predicted less positive perceptions of supportive school climate. The study indicates that students' perceptions of supportive school climate and truancy negatively predict each other over time. Thus, school climate can serve as a target for prevention and intervention efforts to tackle truancy. Moreover, effectively addressing truancy may lead to a more favorable student view of school climate.