Rapid improvements in health and nutrition in developing countries may be ascribed to specific, deliberate, health- and nutrition-related interventions and to changes in the underly- ing social, economic, and health environments. This chapter is concerned with the contribution of specific interventions, while recognizing that improved living standards in the long run provide the essential basis for improved health. Consideration of the environment as the context for interven- tions is crucial in determining their initiation and in modifying their effect, and it must be taken into account when assessing this effect. Undoubtedly much change has stemmed from scientific advances, immunization being a prominent case. However, the organizational aspects of health and nutrition protection are equally.