Background: Emergent evidence suggests a positive school climate may be a promising population-level intervention to promote academic achievement and student well-being. However, researchers have called for expanding the school climate evidence-base to better describe how the construct is associated with student outcomes. The purpose of this study was to determine the associations between 10 school climate domains and academic achievement among middle and high school students. Methods: ANOVAs were used to analyze survey data from 6-12 grade students in a Mid-Atlantic US state (n = 2405, response rate: middle school = 82.4%, 50.5% female; high school = 62.5%, 56.1% female). Results: Significant main effects were found for all school climate domains and varied between middle and high school students apart from academic support. Effect sizes ranged from small to medium, with academic support demonstrating the strongest effects among both middle and high school students. Conclusions: Findings suggest school climate is associated with academic achievement for both middle and high school students. Correctly identifying the role of key aspects of school climate by grade-level may provide improved and developmentally appropriate recommendations for the delivery of instruction and school-based interventions that promote positive school well-being and student performance.