Although much research suggests that intergroup contact reduces prejudice, less research has examined the effects of contact on prosocial intergroup bystander behaviors. The current study examined mediators between White undergraduate women's (N = 139) contact with racial/ethnic minority group members and their intent to help a Black woman at risk for sexual assault. As expected, White women who had more frequent and higher quality contact reported greater intent to intervene. Results showed that the effect of quality intergroup contact was mediated by diversity beliefs, or the attitude that cultural heterogeneity leads to favorable outcomes. These results suggest that promoting high-quality opportunities for intergroup contact and education regarding cultural diversity could promote the safety of racially and ethnically diverse students on predominantly White campuses.