Developing countries have implemented primary health care programs directed primarily at prevention and management of important infectious and nutritional problems of children. Successful programs have emphasized the need for individual and community involvement and have been characterized by responsible government policies for equitable implementation of efficacious and cost-effective health interventions. Unfortunately, developing countries must also face increases in the chronic disease and social problems commonly associated with industrialized countries. Prevention efforts, for example, to reduce tobacco smoking, to modify the diet, to reduce injuries, or to avert environmental contamination, are needed to contain future morbidity and rapidly increasing medical care costs. Developing countries can build on their successful approaches to program implementation and add other measures directed at preservation of health and prevention of disease in adult as well as child populations.