An evaluability assessment was conducted to plan a community-based, multi-strategy approach to physical activity promotion (MSAPAP) to maximize young children's physical activity in an ethno-racially and socio-economically diverse city. This assessment involved consultation with various stakeholders to develop a program logic model to diagrammatically describe the MSAPAP. First, published literature regarding physical activity was reviewed to describe interventions designed to increase children's physical activity and to identify factors that contributed to program effectiveness. Secondly, key informants from mainstream service organizations and smaller community-based agencies were interviewed to determine their views on how to increase physical activity among children and families. A workgroup developed a draft logic model based on the results of the literature review and community needs assessment results. Thirdly, stakeholders were consulted about the draft model. This consisted of 12 focus groups with members of school boards (two sessions), members of community organizations (three sessions), lay home visitors who provide support to mothers of young children in ethno-racially diverse communities (one session), and parents from six cultural groups (six sessions). The logic model was revised based on the findings from this consultation. The final logic model shows children aged 3-8 years as the main target group, and parents and various community members who influence children as intermediate target groups. The MSAPAP is depicted as six strategies, which are clusters of program activities that are conceptually similar: community engagement, community assessment, accessibility, promotion, education and skill development, and inclusive programming. The logic model shows the 'cause and effect' relationships among program activities, shorter-term outcome objectives (e.g. to reduce user fees for physical activity programs) and longer-term outcome objectives (e.g. to increase the proportion of children who are physically active). The extensive community involvement in planning the MSAPAP facilitated a subsequent plan to develop, implement and evaluate selected program activities in the MSAPAP.