An extensive theoretical and qualitative literature stresses the promise of instructional practices and content aligned with the cultural experiences of minority students. Ethnic studies courses provide a growing but controversial example of such “culturally relevant pedagogy.” However, the empirical evidence on the effectiveness of these courses is limited. In this study, we estimate the causal effects of an ethnic studies curriculum piloted in several San Francisco high schools. We rely on a “fuzzy” regression discontinuity design based on the fact that several schools assigned students with eighth-grade GPAs below a threshold to take the course in ninth grade. Our results indicate that assignment to this course increased ninth-grade student attendance by 21 percentage points, GPA by 1.4 grade points, and credits earned by 23. These surprisingly large effects are consistent with the hypothesis that the course reduced dropout rates and suggest that culturally relevant teaching, when implemented in a supportive, high-fidelity context, can provide effective support to at-risk students.