The integration of primary care and mental health in the public sector promises both financial savings and improved care for patients, who benefit from the collaborative treatment of their physical and mental health. Yet integration quickly proves a complex task. With their different models of care, histories, and priorities, the primary care and mental health domains have trouble communicating, much less collaborating. In this issue of New Directions for Mental Health Services, mental health and primary care providers come together to discuss the opportunities and challenges posed by integration. Drawing from their experiences, the authors examine the forces both for and against integration; offer suggestions for effective cooperation between the specialties; and explore the issues of gatekeeping, authorization, and confidentialityThis is the 81st issue of quarterly journal New Directions for Mental Health Services. For more information on the series, please see the New Directions for Mental Health Services page.