Research on friendship and adjustment has traditionally focused on same-sex, same-grade, and same-school peers. Recent evidence, however, suggests that many adolescents have other-sex and other-school friends that significantly impact their adjustment. The purpose of this study was to examine young adolescents’ experiences with mixed-grade friendships (friendships between adolescents in the same school but of different grades), a type of friendship about which little is known. Participants were 179 seventh grade and 178 eighth grade students (55 percent female; M age = 13.2 years, SD = .68) who reported on their same-grade and mixed-grade friendships and loneliness. Peer nominations of same-grade aggression, anxious-withdrawal, victimization and rejection were also collected. Descriptive analyses revealed that 83 percent of students reported having a mixed-grade friend, 36 percent of these friendships being mutual. Adolescents who made mixed-grade nominations and who had mutual mixed-grade friendships reported less loneliness than other adolescents. Results also suggested that mixed-grade friends may protect same-grade friendless girls from feelings of loneliness, and eighth grade same-grade friendless adolescents and anxious-withdrawn boys from victimization. Taken together, findings strongly suggest that mixed-grade friendships are developmentally significant peer relationships during early adolescence.