The term primary care is widely used as if it were consistently defined or well understood. In fact, neither is the case. This paper offers a definition of primary care derived from historical perspectives-from both the United States and abroad. We discuss the evidence for primary care's important functions and international experiences with primary care. We also describe how and why the United States has deviated from this fuller realization of primary care, as well as the steps needed to achieve primary care and health outcomes on a par with those of other developed countries. These include doubling primary care financing to 10-12 percent of total health care spending--a step that would be likely to pay for itself via resulting reductions in overall health spending.