Background/Context: Schools have differential effects on student learning and development, but research has not generated much explanatory evidence of the social-psychological pathway to better achievement outcomes. Explanatory evidence of how normative conditions enable students to thrive is particularly relevant in the urban context where attention disproportionately centers on the pathology of these environments rather than social attributes that contribute to student growth. Research Purpose: Our purpose in this study was to determine if a self-regulatory climate works through student self-regulation to influence academic achievement. We hypothesized that (1) self-regulatory climate explains school-level differences in self-regulated learning, and (2) self-regulated learning mediates the relationship between self-regulatory climate and math achievement. Research Design: We used ex post facto survey data from students and teachers in 80 elementary and secondary schools from a large, southwestern urban school district. A multilevel modeling building process in HLM 7.0 was used to test our hypotheses. Results: Both hypotheses were supported. Self-regulatory climate explained significant school-level variance in self-regulated learning. Additionally, student self-regulated learning mediated the relationship between self-regulatory climate and math achievement. Conclusions: Our results suggest that schools, like teachers, have differential effects on the motivational resources of students, with self-regulatory climate being an essential social condition for self-regulation and achievement. We believe self-regulatory climate has value for educators seeking to provide equitable learning opportunities for all students and for researchers seeking to account for achievement differences attributed to schools. In both cases, self-regulatory climate advances a construct and measure that conceptualizes and operationalizes school-level support for psychological needs.