Small groups of friends—or peer groups—are a central feature of adolescence that contribute to the development of social identity and feelings of self-worth for group members. Additionally, adolescents value music highly and view it as a vital part of their lives. The purpose of this study was to examine and clarify the extent to which adolescents use music as an identity resource in small peer groups. Using Tajfel and Turner’s Social Identity Theory as a framework, I conducted a collective case study to understand (a) the ways in which adolescents use music to form and maintain a peer group, (b) the extent to which peer groups use music for the social categorization and stereotyping of other groups of adolescents, (c) the ways by which adolescents use music associated with their peer group to maintain a positive self-concept, and (d) how the peer group influences members’ enjoyment of music and music participation. I conducted group interviews with three adolescent peer groups that contained 5–8 seventh- and eighth-grade students. The peer group members shared experiences of bonding and socializing as a part of a peer group, and described time spent in their music classes. During the discussions, group members explained the role that music plays in their lives. The group members explained their peer group in the context of the school, describing instances of social categorization and stereotyping, in-group and out-group distinction, and self-concept maintenance made from comparisons to the out-groups. The participants discussed their views on school music courses, advocating for the implementation of new classes that included non-traditional instruments and the inclusion of more popular styles of music. Keywords: social identity, adolescent peer groups, in-group, out-group, social categorization, self-concept, stereotyping, adolescence music preference, positive distinctness