Background: Few studies have examined school physical activity policies to assess dose–response on student outcomes. The purpose of this study was to evaluate the association between health-promoting physical activity policies in elementary schools and physical activity behavior. Methods: In this cross-sectional study, physical activity was assessed using self-report measures in fourth-grade students in Texas (N = 1958, x = 9.66 y) from the School Physical Activity and Nutrition (SPAN) survey. School policies were assessed using the number of health-promoting policies in place taken from the SPAN School Health Survey with principals and their proxies. Multiple linear regressions adjusted for student- and school-level confounders and school clustering were performed. Results: School physical activity policies were significantly associated with student-level physical activity behavior (P < .05), even after controlling for the student- and school-level confounding variables. The interactions between physical activity policy-by-economic disadvantage (P < .01) and between physical activity policy-by-geographic strata (P < .01) were both significant, with stronger direct effects of policies on student physical activity for economically disadvantaged schools and major urban schools. Conclusion: Results from this study provide evidence for the importance of school-based health policies and practices in potentially reducing health disparities, especially in low-income and urban schools.