Collaborative partnerships (people and organizations from multiple sectors working together in common purpose) are a prominent strategy for community health improvement. This review examines evidence about the effects of collaborative partnerships on (a) community and systems change (environmental changes), (b) community-wide behavior change, and (c) more distant population-level health outcomes. We also consider the conditions and factors that may determine whether collaborative partnerships are effective. The review concludes with specific recommendations designed to enhance research and practice and to set conditions for promoting community health.