This article summarizes an extensive review of South American experiences with primary health care since the Declaration of Alma-Ata. It aims to address the following specific questions: What are the enabling and constraining historical and structural conditions for primary health care policies and practices? How has health care reform supported or undermined primary health care? What evidence exists on the effectiveness of primary health care? What strategies are common to best practices? What evidence exists on the roles of citizen participation and intersectoral action? And finally, what are the policy lessons to be learned from these experiences? Narrative synthesis was used to identify and examine patterns in the data consistent with these questions. Conditions that were found to promote successful implementation of primary health care are outlined, together with features of effective primary health care systems that help create more equitable health services and health outcomes.