Social impact entertainment advocates and participants in Hollywood’s nascent ‘social impact storytelling’ scene attempt to leverage the cultural influence of popular media on behalf of prosocial and public health causes: they promote, facilitate consultations on, and attempt to integrate social impact content into entertainment programming. The central questions of this dissertation, based on sixteen months of ethnographic fieldwork, involve what kinds of ideologies of social change and theories of communication shaped participants’ everyday practices, structured advocate-industry relationships, and influenced the popular narratives that emerged from advocate-Hollywood collaborations. The project sought to understand how so-called “social impact” topics – primarily issues regarding public health and the social determinants of health -- were being formulated, resisted, transformed, and articulated through and alongside popular narratives. Of particular interest were how the practices and ideologies operating in these contexts might relate to larger cultural discourses about social justice and social change, the potentialities of narrative, contemporary humanitarian ideals, and ideas about responsive ethical subjectivity in relation to others’ stories. Through an ethnographic investigation of social impact media advocacy in contemporary Hollywood, this dissertation explores the landscape and configuration of contemporary social impact media/social impact storytelling movements, their antecedents, recent evolutions, and some of the implications of their current trajectories.