The health care system in the United States, plagued by spiraling costs, unequal access, and uneven quality, can find its best chance of improving the health of the population through the improvement of behavioral health services. It is in this area that the largest potential payoff in reduction of morbidity and mortality and increased cost-effectiveness of care can be found. A review of the evidence shows that many forms of behavioral health services, particularly when delivered as part of primary medical care, can be central to such an improvement. The evidence supports many but not all behavioral health services when delivered in settings in which people will accept these services under particular administrative and fiscal structures.Keywords: economics, cost offset, behavioral health, psychology, medical settings ALEXANDER BLOUNT received his EdD in counseling from the University of Massachusetts at Amherst. He is professor of clinical family medicine at the University of Massachusetts Medical School and director of behavioral science in the Department of Family Medicine and Community Health. He is chair of the Collaborative Family Healthcare Association. His areas of professional interest include the integration of behavioral health services into primary care settings and the training of primary care psychologists and family medicine residents. MICHAEL SCHOENBAUM received his PhD in economics from the University of Michigan. He is a researcher for the RAND Corporation. His interests include analyses of the Palestinian health system, identification of policy options for improving clinical performance and economic viability in health care, economic analyses for national trials to improve care for depression, and Web-based modeling and decision-support tools to help consumers make health benefits choices. ROGER KATHOL received his MD from the University of Kansas School of Medicine. He completed an internship in internal medicine at Good Samaritan Hospital in Phoenix, Arizona; residencies in psychiatry and internal medicine at the University of Iowa in Iowa City; and a year of endocrinology fellowship in Wellington, New Zealand. He is adjunct professor of internal medicine and psychiatry at the University of Minnesota Medical School. He has extensive experience in the integration of general medical and behavioral health care. He has international expertise in the development and operation of cross-disciplinary programs and services for clinics and hospitals; health plans; software vendors; case, disease, and disability management organizations; employee assistance programs; and employers. BRUCE L. ROLLMAN received his MD from Jefferson Medical School and his MPH from Johns Hopkins Medical School. He is an associate professor of medicine and psychiatry at the Center for Research on Health Care at the University of Pittsburgh. He is involved with the planning and implementation of clinical trials to improve the quality of treatment for depression and anxiety disorders in primary care settings and for patients wi...