Despite the often-crucial roles played by music within theatre-based public health promotion strategies, theoretical explorations regarding music within applied theatre literatures remain largely underdeveloped. This article highlights musicking -- a reconceptualization of music from an object to a participatory act that can profoundly influence relationships and spaces -- as an approach to understanding the various roles that music can play within applied theatre programmes. The article draws from ethnographic accounts of an HIV/AIDS applied theatre group in South Africa to advocate for increased recognition of musicking as a robust theoretical and methodological component within applied theatre praxis.