The involvement of the sport and recreation sector as a setting for health promotion is a new strategy implemented by health policy makers and strategic planners. Strategies to promote and sustain health promotion activities are important considering the risk that programs may cease after initial funding ends. This study explored the factors affecting the sustainability of a sport- and recreation-based health promotion program. A stratified sampling method was used to select four of the nine Regional Sports Assemblies (RSAs) that delivered a state-wide health promotion program funded by the Victorian Health Promotion Foundation in Australia. Data were collected from in-depth interviews with four Executive Officers (EOs) and focus group discussions with their Boards of Management. A sustainability checklist with pre-specified dimensions (e.g. organisational setting, broader community environment, and program design and implementation) guided data collection and analysis. The results showed that the organisational setting and the broader community environment supported program institutionalisation; whilst the design and implementation of the program worked against institutionalisation. The capacity of the organisations to generate new funds for the program was limited; the relationship between the central funding organisation and the Boards of Management was weak; and the program did not support the retention of staff. The engagement of sport and recreation organisations has potential to facilitate health promotion and public health. To enhance organisational capacity and achieve program sustainability, it is important that organisational processes, structures, and resources that support long-term health promotion practice are effectively and efficiently planned and managed.