The health and nutritional status of children aged 5 and under was assessed in three villages in Siaya District of western Kenya. A cross-sectional survey was conducted among 121 adults and 175 children during July 2002. Primary caretakers were interviewed during home visits to assess agricultural and sanitation resources, child feeding practices, and the nutritional status of their children aged 5 years and under. Through anthropometry, the prevalence of underweight, stunting and wasting were determined: 30 per cent were underweight, 47 per cent were stunted, and 7 per cent were wasted. Predictors of undernutrition were analysed using logistic regression controlling for age, sex, and SES, and four major findings emerged. First, children in their second year of life were more likely to be underweight and stunted. Second, children who were introduced to foods early had an increased risk of being underweight. Third, up-to-date vaccinations were protective against stunting, while reports of having upper respiratory infections or other illness in the past month predicted underweight. Finally, living with non-biological parents significantly increased risk of stunting. Emphasis should be placed on current immunization, prolonging exclusive breastfeeding, and improving access to nutrient-rich foods among adopted children and their families via community-based nutrition interventions.