This research examines how midstream social marketing programmes that adopt a relational and community-based approach create opportunities for individuals to make incremental changes to health behaviour. Specifically, it applies Bourdieusian theory to explore how interactions between community healthcare workers (CHWs) and members of the public generate impetus for change and foster individual agency for improved health. Qualitative interviews were carried out with members of the public and CHWs engaged in a Smokefree homes and cars initiative. The findings suggest that although CHWs are challenged by resource constraints, their practices in working with individuals and families build trust and enable dialogue that bridges smoking-related health insight with home logics. These interactions can promote individual agency with a transformative effect through small changes to smoking-related dispositions, norms and practices. However, tensions with the habitus of other household members and other capital deficits can inhibit progress towards embedding new practices. The study concludes that interventions built upon community relationships show potential for addressing limitations of information-focused campaigns but there is a need to also respond to key social structures relating to the field of action for new health dispositions to become embedded in practice.