Extending work documenting historical resource inequities across U.S. schools, we examined how school financial and social resources mediate the relationship between family income and student achievement, and tested how these associations varied by race and ethnicity. Merging administrative school data sources to a nationally representative sample of U.S. elementary students, and employing structural equation modeling, we found that family income selected all children into more highly socially resourced schools, with significantly stronger effects for White children relative to students of color. Contrary to expectations, school financial and social resources were not significantly associated overall with achievement.