Research examining links between racial-ethnic microaggressions and educational and psychological outcomes can be improved with the development of brief and reliable measurement tools. Our brief School-Based Racial and Ethnic Microaggressions Scale addresses this gap. First, we examined the prevalence of school-based microaggressions among an analytic sample of 462 Black and Latinx students attending five historically White universities in the Midwest. Then, we examined the association between school-based microaggressions and depressive symptoms and academic achievement. An exploratory principal components analysis of Wave 1 data and a confirmatory factor analysis of Wave 3 data validated a three-factor model: (a) Academic Inferiority, (b) Expectations of Aggression, and (c) Stereotypical Misrepresentations. Students' exposure to microaggressions and its effects were conditional on individual and school characteristics.