The “Collective Music-Making as Social Interaction” (CMSI) study was conducted at Vic University, Catalonia. The project was a music-based arts and health workshop, featuring as part of the University’s Art as a Tool for Social Transformation program, aimed to explore how music and the design of bespoke notation can be used in groups to support social interaction among participants. Findings identified within the experiences of participants included discovery, expression, perception, recognition, imagination, communication, cohesiveness, confidence, and self-esteem. The project reveals how a creative, collaborative process can demonstrate a group’s capacity to learn new ways of socially interacting and communicating. The study also shows how the collective product (both composition and ensemble performance) is representative of such social interaction. It is suggested that designing musical notation in collective workshops can facilitate healthy engagement between individuals, proposing extensions of the model for use with arts on prescription and social prescribing service users.