Many disciplines of musicology are dedicated to unravelling the connections between music and society. However, we lack a thorough understanding of music’s role in actively changing society. This thesis contributes to remedying that with a focus on musical participation and improvisation. It specifically aims to (1) understand how music contributes to social change in general; (2) discover what kinds of social changes tend to be effectively animated by musical participation and improvisation; and (3) explain why such participatory and improvisatory musics are effective. This occurs across the theoretical, empirical, and practical domains. The first half of the thesis synthesises existing literature and original empirical findings to produce a framework explaining what social change is, how musical participation and improvisation can contribute to it, and through which mechanisms this occurs. It proposes four themes that participation and improvisation afford, namely uniting heterogeneity, direct experience, enhanced agency, and novelty and adaptation. I then use this framework to analyse the cacerolazo protests during the 2001-2002 Argentine financial crisis to understand this participatory and improvisatory music’s capacity for large-scale change. Finally, these findings are applied practically in a highly participatory and improvisatory musical created in collaboration with local First Nations musicians entitled Togetherness Through Music. The intention of this event was to positively transform the meta-conflict between First Nations and settler Australians, and Chapter Five's evaluation of this event furthers our understanding of how participation and improvisation might effectively do this. Together, this work will enhance our understanding of musical participation and improvisation’s role in social change at various levels of society. It will also demonstrate the best practices for changemakers that intend to use them to better the world