The effects of school-based ethnic diversity on student well-being and race-related views were examined during the first year in middle school. To capture the dynamic nature of ethnic exposure, diversity was assessed both at the school-level (n = 26) and based on academic course enrollments of African American, Asian, Latino, and White students (n = 4,302; M = 11.33 years). Across all four pan-ethnic groups, school-level ethnic diversity was associated with lower sense of vulnerability (i.e., feeling safer, less victimized, and less lonely) as well as perceptions of teachers' fair and equal treatment of ethnic groups and lower out-group distance. Underscoring the role of individual experiences, exposure to diversity in academic classes moderated the association between school-level diversity and the two aforementioned race-related views.