Abstract: This study was undertaken to document the contributions of the School Lunch Program (SLP) to the diets of Mexican American migrant children in the U.S. Contributions were measured at the individual level via nutrient analysis of the child's daily food intake and food group analysis. A critical medical anthropology theoretical framework led to further analysis of the SLP's history and objectives in the broader context of the health system in a capitalist society. The ultimate goal was to elucidate the impact of policies and priorities established at the system level on the nutritional status of a group of migrant children. Nutritional data were collected using the three-day, 24 hour recall method. Thirty-three (33) Mexican American migrant children in Florida, and sixteen (16) children of the same background in New York were interviewed. Sociodemographic information was collected by means of a questionnaire. Ethnographic observations provided the necessary background to interpret both types of data. The significance of the contribution of the School Lunch Program to the diet of migrant children was revealed by comparison to the contributions of the home. The school lunch was designed to provide 1/3 of the Recommended Daily Allowances (RDA) for all nutrients. This analysis, however, showed that relative to the home, the school lunch accounted for one-half of the RDAs for calcium and vitamin D. The findings also revealed an inadequate consumption of fresh fruits and vegetables, as well as an over-reliance on fat and protein as sources of calories. Given the importance of calcium and vitamin D for the healthy bone development in children, it is suggested that without the school lunch, migrant children sampled in this study could be at risk for health problems related to inadequate intake of these two nutrients. The role of the SLP is also emphasized in terms of reversing adverse dietary patterns of fat, protein, fruits and vegetable consumption through exposure of migrant children to nutritious, varied and balanced diets. A critical medical anthropology interpretation of these results proposes that the underlying cause of nutritional problems of the poor may be tied to the nature of health under capitalism.