This article examines how peer interactions in college organizations (Greek, ethnic, and religious) affect interracial friendships, including whether peer interaction in student organizations mediates the relationship between structural diversity and interracial friendship. Involvement in ethnic student organizations was non-significant; involvement in Greek or religious student organizations was a negative predictor. Greek involvement mediated the relationship between structural diversity and interracial friendship; greater structural diversity decreased the likelihood of students interacting with peers from Greek organizations, which had a positive effect on interracial friendship. Findings suggest that structural diversity acts as a buffer against the negative influence of Greek organizations on interracial friendship. (Contains 3 tables and 2 figures. )