Purpose -This paper contributes to emerging discourse about social movements in social marketing by examining how tensions, issues and challenges may arise in areas of social change that have attracted social movements and the ways actors can come together to drive inclusive social change agendas.Design/methodology/approach -Through the lens of new social movement theory, a case study of the interactions and dynamics between fat activists and obesity prevention public health actors is examined. This is undertaken through a multi-method qualitative analysis of interview and archival blog data of fat activists located in Australia, which was compared with the campaign materials and formative and evaluative research related to two high profile Australian Government funded anti-obesity campaigns.Findings -The case analysis highlights the disconnect between public health actors and the marginalized voices of those they are meant to be representing. Whilst public health actors characterise obesity as a social issue of individual responsibility, disease and rational-decision making; fat activists frame a competing collective identity of well-being, support and self-acceptance that characterise their social change efforts.Research limitations/implications -This research highlights how complexities arise but can potentially be overcome in creating inclusive social change coalitions that incorporate the voices of citizen groups whom have mobilised into social movements. Specifically, we highlight the importance of generating a common language around obesity, the significance of collaborative and supportive relations and the need to create common unity through emotional investment and returns -a departure from the highly rational approaches taken by most social change programs.Practical implications -Obesity is a complex social issue marked by conflict and contestation between those who are obese and the very actors working to support them. Our research contends that creating an inclusive social change coalition between these stakeholders will require a shift towards language anchored in well-being as opposed to disease, relations defined by support as opposed to an emphasis on individual responsibility and emotional investments that work to bolster self-acceptance in place of rational appeals as to the "correct" behaviours one should chose to engage in. Such steps will ensure social change program design is collaborative and incorporates the lived experiences of the very citizens such initiatives are targeted towards.Originality/value -We contribute to wider discussions in social marketing about the development of holistic and progressive, multi-stakeholder, multi-level programs by advocating that inclusive social change JSOCM 8,4 354 coalitions united through the collective identity elements of cognitions and language, relational ties and emotional investment offer an important step forward in tackling the wicked problems that social marketers work to address.