The degree to which a reformed U.S. health care system relies on an ad
equate supply of primary care physicians will determine the urgency of
change in the composition of the medical workforce. In many areas of
the United States, the demand for primary care physicians, particularl
y in managed care settings, far exceeds the supply. In contrast, repor
ts of reduced practice opportunities for medical and surgical subspeci
alists in the same settings are increasing. As opportunities for and i
ncomes of primary care physicians are enhanced, some medical subspecia
lists may seek retraining in primary care. This article provides a con
text for understanding the development of physician retraining program
s, examines precedents for retraining physicians, describes four possi
ble pathways through which medical subspecialists might acquire primar
y care training, and emphasizes the importance of defining the scope o
f practice and necessary skills for providing primary care. Obstacles
to retraining appear to be economic (Who will pay? Is the cost worth t
he benefit?) and jurisdictional (Who will define core competencies? Wh
o will credential programs and trainees?). The current absence of dema
nd for such retraining programs suggests either that marketplace-induc
ed changes will not take place or that the notion of a primary care pr
ovider shortage and an oversupply of medical subspecialists is oversta
ted. The inclusion of physician retraining programs in proposed health
reform legislation suggests that policymakers are convinced that such
programs offer one viable solution to the nation's medical workforce
needs.