Child malnutrition is pervasive in almost every developing country. Economic growth can lead to better child nutrition, but the size and nature of this effect can vary widely across countries. This first part of this paper examines the impact of increased household income on children's nutritional status on Vietnam, a country with a high rate of economic growth in the 1990s. It finds that increases in household incomes lead to statistically significant improvements in children's nutritional status, but the size of this effect explains only a small proportion of the reduction in child malnutrition in Vietnam in the 1990s. This suggests that something else occurred in Vietnam during those years that reduced child malnutrition. A preliminary analysis of data on health services in rural areas suggests that specific types of services, particularly equipment for measuring and monitoring child growth, lead to improved child nutrition.