A five-month longitudinal study in a Nepali village showed consistent behavioral differences between undernourished and more adequately nourished infants aged seven through 18 months. Caregivers' behavior, on the other hand, showed no differences as a function of the children's nutritional condition. Comparisons with two earlier cross-sectional studies in different cultural settings suggest that, regardless of the cultural setting, infant behavioral development appears altered as a function of undernutrition. Maternal caregiving behavior seems culturally determined and need not be a contributing factor to infant undernutrition in developing countries.