David Mechanic has been a pioneering leader in the social and behavioral sciences of health, health services, and health and mental health policy for more than fifty years. One of David's most distinctive qualities has been his vision in identifying trends and defining new research areas and perspectives in health care policy. His early work on how methods of physician payment by capitation and fee-for-service in England and the United States affected physicians' responses to patients and patient care addressed present challenges and many ongoing studies of payment mechanisms. His papers on rationing of health care established a framework for examining alternative allocation mechanisms and just decision making. Influential papers dealt with risk selection, policy challenges in managed care, reducing racial disparities, trust relationships between patients, doctors, and the public and health institutions, and the predicaments of health reform. Focusing on the implementation of the Affordable Care Act, David explored its opportunities and challenges especially in providing comprehensive and effective behavioral health services. A hallmark of his work has been his redirecting our attention to the most severely ill and those in greatest need. Less visible is the leadership and institution building endeavors and the many honors David has received.