Health care reform in the United States and elsewhere raises many questions about equity and effectiveness of health services. Although the impetus has been cost containment, the reforms have often been justified on the grounds that they will enhance primary care. In this article, health care reform efforts are divided into two types: market-driven, demand-based systems versus systems predicated on meeting population health needs. The two "scenarios" are contrasted with regard to their likely impact on the attainment of primary care characteristics: first-contact care, longitudinality, comprehensive services, and coordination. Since the ultimate outcome of these reforms cannot be predicted, there is compelling need for evaluating them as they proceed.