This research is a multi-modal folio consisting of collaborative scores, recordings and short films housed on the thesis website, and exegetical writing comprising an introduction and background to collaborative composition, case studies, narratives and interviews with other practitioners about their collaborative artistic agency. The research investigates different approaches to collaborative composition in a variety of settings. Each of these collaborative works involved research, creation and performance of new musical works for both professional and amateur musicians as well as participants without prior musical knowledge or skills. The compositional methods employed in these projects range from direct individual authorship of musical works to the creation of a body of artistic practice formed during collaborative process-based workshops. The thesis investigates the compositional processes involved in each case, contextualising and mapping their interrelationships in order to present a series of recommendations for collaborative compositional agency. Key references are to the writings of Nicolas Bourriaud, Clair Bishop, Richard Sennet with regard to their perspectives on collaboration and the relational and social fabric of the artist in society today. The thesis uses a range of approaches—including reflective assessment of compositional practice during workshops and their presentations, as well as documentation of artistic outcomes and my own reassessment after project conclusion. My lens is as a composer and leader of such projects guiding democratic processes during collaborations which foster inclusivity and creativity.