Regional health systems attempting to achieve the vertical integration of health services ultimately must achieve clinical integration. The thesis of this article is that vertical integration in health care involves the coordination of inputs (equipment, supplies, human resources, information, and technology) and intermediate outputs (preventive, diagnostic, acute, chronic, and rehabilitative services) to attain the end goal of optimal personal health. Given this perspective on vertical integration, the coordination of specialty services and primary care within a system structure—that is, the clinical integration of patient care—is central to the realization of vertically integrated regional health systems. Institution-level and environmental factors that facilitate and challenge the attainment of clinical integration are elucidated, and a set of clinical integrating mechanisms are outlined with presentation of real-world examples of those mechanisms. The analysis concludes by summarizing the next steps in realizing the vision of clinically integrated, regional systems of health care.