In low-income neighborhoods without supermarkets, lack of healthy food access often is exacerbated by the saturation of small corner stores with tobacco and unhealthy foods and beverages. We describe a municipal healthy retail program in San Francisco, California, focusing on the role of a local coalition in program implementation and outcomes in the city's low income Tenderloin neighborhood. By incentivizing selected corner stores to become healthy retailers, and through community engagement and cross-sector partnerships, the program is seeing promising outcomes, including a "ripple effect" of improvement across nonparticipating neighborhood stores.

As resources for health promotion become more constricted, it is increasingly important to collaborate across sectors, including the private sector. Although many excellent models for cross-sector collaboration have shown promise in the health field, collective impact (CI), an emerging model for creating larger scale change, has yet to receive much study. Complementing earlier collaboration approaches, CI has five core tenets: a shared agenda, shared measurement systems, mutually reinforcing activities, continuous communication, and a central infrastructure. In this article, we describe the CI model and its key dimensions and constructs. We briefly compare CI to community coalition action theory and discuss our use of the latter to provide needed detail as we apply CI in a critical case study analysis of the Tenderloin Healthy Corner Store Coalition in San Francisco, California. Using Yin's multimethod approach, we illustrate how CI strategies, augmented by the community coalition action theory, are being used, and with what successes or challenges, to help affect community- and policy-level change to reduce tobacco and alcohol advertising and sales, while improving healthy, affordable, and sustainable food access. We discuss the strengths and weaknesses of CI as a framework for health promotion, as well as the benefits, challenges, and initial outcomes of the healthy retail project and its opportunities for scale-up. Implications for health promotion practice and research also are discussed.