AbstractThis report describes an action‐research project which contributed to mobilizing a community to respond to homelessness in a large Southern California city. The project involved collaboration among a city‐sponsored Task Force, a grass‐roots coalition, and a university. The project core was a needs assessment which served as a basis for advocacy by the Task Force and a coalition of service providers and citizens. Empirical findings are reported along with political impacts including the ultimate fate of recommendations adopted by city government. An analysis of factors constraining policies relating to homelessness at the level of mid‐size municipalities suggests that advocacy strategies must link local efforts with regional, state, and/or national levels to be effective. This conclusion, if valid and general, has significant implications for the theory and practice of community psy