The author reviews the fundamental changes that have taken place in the U.S. health care system since 1935, predicts what that system will be like in the early part of the next century, and discusses the implications for academic medicine. Specifically, he maintains that physicians being trained today will practice within the context of large organizations, with payment for care being either by employment-based insurance or by some form of government-subsidized insurance. Care will be delivered across diffuse networks, and most physicians will be paid according to capitation or salary schemes. The role of technology will be high and will revolutionize the health care system, which will be focused on prevention and maintenance of function rather than cure. The success of the system will be measured by its cost-effectiveness and by how well it works to maintain the mental, social, and physical functions of its participants. Finally, the obligation of the physician will be not only to individual patients but also to the populations and communities from which patients come. Training physicians to meet these obligations and to function effectively in the revolutionized system will involve changes in medical education to more appropriately socialize students into the next century's medical culture. The author reviews in detail the various elements of the medical culture that must be addressed by medical education, gives examples of the kinds of changes that must be made, and describes efforts at his school to reinforce across the curriculum the population-based model of clinical practice.