This qualitative review of 57 published case reports aimed to analyze primary care and public health integration efforts in 45 states to summarize collaboration aims, participants, and systemic, organizational, and interactional success determinants. Chronic disease management, maternal and child health, and wellness and health promotion were the most commonly reported aims of collaboration between primary care and public health entities in the United States. Typical participants were government public health structures, health delivery systems, communities, academia, state professional medical associations, and employers and businesses. Systemic, organizational, and interactional determinants included adequate funding, multiple stakeholder engagement, leadership, data and information sharing, capitalization on collaborator resources, community engagement, steering committees, effective communication, regular meetings, shared mission, vision, and goals, previous positive relationships, collaborations, and partnerships. The present study contributes to the body of knowledge of when, where, and under what contextual circumstances collaboration and integration have been perceived as effective. Future research could extrapolate which determinants are more essential than others and focus on how systemic, organizational, and interactional factors are interrelated. To advance the practice of successful integration between primary care and public health entities, longitudinal research is needed to examine the degree of integration and sustainability.