A dramatic shift in the postgraduate career choices of medical school graduates toward primary care occurred during the mid-1990s. While some attributed this shift to changes in medical school curricula, perceptions stemming from marketplace reforms were probably responsible. For the most part, these perceptions were probably generated through informal communications among medical students and through the media. More recently, additional marketplace influences, such as the consumer backlash toward managed care and unrealized gains in primary care physicians' personal incomes, may have fostered contrasting perceptions among medical students, leading to career choices away from primary care, particularly family practice. The authors offer two recommendations for enhancing the knowledge of medical students concerning workforce supply and career opportunities: an educational seminar in the second or third year of medical school, and a public-private partnership between the Bureau of Health Professions and the Association of American Medical Colleges to create a national database about the shape of the primary care and specialty workforces, accessible through the Internet for educators, students, and policymakers. The authors conclude that appropriate career counseling through these efficient methods could avoid future abrupt swings in specialty choices of medical school graduates and may facilitate a more predictable physician workforce supply.