Results provide clear and consistent evidence for high specific music similarity and moderate overall music similarity in early adolescent mutual friendships. Both similarity in specific music dimensions and similarity in overall music preferences were found to be higher among mutual friends than among randomly paired adolescents, suggesting that early adolescents are more similar in specific music dimensions and overall music preferences to their friend than they are to other adolescents. This suggests that individuals may gain a social identity from the music-based groups to which they belong and will therefore adopt similar music preferences to those of the individuals in their group in an attempt to foster self-esteem and feelings of belonging. The similarity-attraction hypothesis and the assortative mating perspective suggest that individuals are most attracted to other people who have similar attitudes, values, and behaviors, and personality characteristics, and according to the results of the present study, similarity in musical preferences. Data were collected from 566 Dutch adolescents participating in an ongoing longitudinal study that examined the relationships of Dutch adolescents with parents and peers as well as their emotional states. Tables and references