The combined search strategy yielded 6125 articles of which 114 were included. Systemic-level factors influencing collaboration included: government involvement, policy and fit with local needs; funding and resource factors, power and control issues; and education and training. Lack of a common agenda; knowledge and resource limitations; leadership, management and accountability issues; geographic proximity of partners; and shared protocols, tools and information sharing were influential at the organizational level. Interpersonal factors included having a shared purpose; philosophy and beliefs; clear roles and positive relationships; and effective communication and decision-making strategies. Reported benefits of collaboration included: improved chronic disease management; communicable disease control; and maternal child health. More research is needed to explore the conditions and contexts in which collaboration between PC and PH makes most sense and potential gains outweigh the associated risks and costs.