School climate is theoretically important for the academic achievement of students in urban schools because safety and support at school may compensate for negative structural forces experienced elsewhere. There is strong evidence for an association between school climate and student achievement, but little suggests the association's directionality. This study uses a unique longitudinal, student-level data set from a large urban district that combines standardized test scores, student survey data, and cross-lagged panel modeling to build evidence for this directionality. In general, findings suggest that in the elementary and middle grades, perceptions of school climate are better predictors of later academic achievement than the reverse. However, the directionality reverses in high school, with achievement predicting later school-climate perceptions.