As part of the implementation of the country's Unified Health System (Sistema Único de Saúde), the Brazilian Government created, in the second half of the 1990s, the Family Health Program (FHP) (Programa de Saúde da Família), based on community-oriented, multidisciplinary care serving people organized into small groups. For this study, we evaluated the implementation of the FHP, based on three criteria: (1) the construction of the program as an entry point for most health needs and for access to specialized care, (2) the program's linkages with a comprehensive network of health services, and (3) the incorporation of new care practices into the health system. We found that the implementation of the FHP was far from uniform. In some municipalities the FHP is a focused program that runs in parallel with other primary care efforts. However, in other municipalities the FHP is viewed as a strategy aimed at changing the primary care model, and it partially or completely replaces preexisting primary care health units. Our research confirms a trend toward incremental change in the primary care model in Brazil. However, the expansion of the FHP in large urban areas faces several obstacles to guaranteeing all individuals access to comprehensive care with adequate clinical and collective health services, including secondary and tertiary care. The positive results that we found with some of the experiences with the FHP indicate that, in addition to increased federal financial incentives, the success of the FHP depends on creative local strategies to deal with Brazil's diversity.