Purpose: The purposes of the present study were to (a) compare context-specific conceptions of friendship quality in youth sport and music, and (b) determine how friendship quality is related to motivational beliefs in sport and music. Method: Adolescents (N = 366; M[subscript age] = 12.9, SD = 1.0) who were involved in both organized sport and music completed measures of domain-specific friendship quality, perceived competence, enjoyment, anxiety, and motivational orientation. Results: For purpose one, a repeated-measures MANOVA revealed that (a) boys and girls rated their best sport friends higher in self-esteem enhancement and supportiveness than their best music friends, (b) boys rated their best sport friends higher in loyalty and intimacy, things in common, companionship and pleasant play, and conflict resolution than their best music friends, (c) girls rated positive friendship quality dimensions higher than boys, and (d) there were no domain or gender differences in friendship conflict. For purpose two, structural equation modeling revealed that (a) for sport, positive friendship quality dimensions were directly associated with perceived competence and indirectly associated with enjoyment, anxiety, and motivational orientation, and (b) for music, positive friendship quality "and" friendship conflict were related to competence motivation variables. Conclusion: Collectively, findings indicate domain differences in friendship quality and the relationship between friendship quality and motivational outcomes in sport and music. Despite some domain differences, findings demonstrate the significance of friendship quality for adolescents involved in sport and music.