As the focus of health promotion moves from individuals to organizations, communities and broader social policy, the models that guide public health program planning and development need reexamination. Public health nurses are gaining experience in strengthening and supporting the ability of communities to grow and change. This study aimed to illuminate the process. Data, gathered as part of an action research project to develop individual and community-based strategies to decrease isolation in frail older adults, provided a rich source of qualitative data. Analysis was directed toward identifying the factors and processes of capacity-building. The emerging model was clarified and partially validated with academics and practitioners from health promotion programs across the age span. Four stages of building collective capacity were identified: identifying common ground, working cooperatively, working in partnership, and working across the community. At each stage, processes of relationship building, project management and capacity-building resulted in stage specific products. A model of building collective capacity, grounded in community health practice and supported by the literature provides a base for developing practice indicators, and practice guidelines which will strengthen the ability to reach health goals.