Unexpectedly, the use of health care services has been found to differ substantially across subgroups of a population covered by health insurance. In the Medicare program, persons at risk of poor health tend to use fewer of the types of services that healthier persons use to improve health and prevent disease. Relatively little is known about why patterns of health care among the elderly differ by race and socioeconomic status (SES). That disparities occur so persistently in a program such as Medicare, which was expected to equalize access to care, indicates that there are limitations to what health insurance alone can do to assure equal access to health care. The challenge is to determine what our society can do to ameliorate disparities i...