To examine the unique functions of same‐ and cross‐ethnic friendships, Latino (n = 536) and African American (n = 396) sixth‐grade students (Mage = 11.5 years) were recruited from 66 classrooms in 10 middle schools that varied in ethnic diversity. Participants reported on the number of same‐ and cross‐ethnic friends, perceived vulnerability, friendship quality, and the private regard dimension of ethnic identity. Whereas same‐ethnic friendships were uniquely associated with stronger private regard, more ethnic diversity and cross‐ethnic friendships were uniquely associated with less perceived vulnerability. Multilevel structural equation modeling tested whether cross‐ethnic friendships mediated the diversity‐vulnerability relation. Although cross‐ethnic friendships did not significantly mediate this relation at the classroom level, these friendships predicted less vulnerability at the individual student level.