The present study examines the role of similarity in music preferences in the formation and discontinuation of friendships over a 1-year period. Questionnaire data were gathered from 283 Dutch same-sex mutual best friends (mean age = 12.97) in two waves with a 1-year interval. Results show consistent evidence for high similarity in specific music dimensions among friends at both waves. Moderate similarity was found in the overall patterning of preferences for music genres at both waves, even after controlling for similarity in social background. Specific music similarity in more non-mainstream music dimensions and overall music similarity at Wave 1 were related to selecting a new friend at Wave 2. However, similarity in music preferences was not related to the discontinuation of an existing friendship at Wave 2. Thus, results suggest that similarity in music preferences is related to friendship formation, and not to friendship discontinuation. (Contains 3 tables.)