Anaemia and stunting are prevalent nutritional problems among children of low-income countries that have profound effects on development, morbidity, and mortality. Many use a single conceptual framework to identify the basic determinants of these and other forms of malnutrition. One would expect that problems with matching underlying determinants should co-occur in affected individuals to a greater degree than by chance. In 2 populations of children—ages 6–18 months in Bihar, India, (n = 5,664) and 6–36 months in Lambayeque, Peru (n = 688)—we measured the frequency of the co-occurrence of anaemia and stunting. We compared this value with the value expected by chance, the product of the prevalence of anaemia and stunting, using a chi-square test. We also built logistic regression models for each condition. The frequency of co-occurrence in the Indian population was 21.5%, and in the Peruvian population, it was 30.4%, which are similar to frequencies expected by chance, 21.3% (p =.97) and 31.5% (p =.85). In Peru, anaemia was associated with age and consumption of treated water. Stunting was associated with age, sex, dietary diversity, hand washing, language spoken, and wealth. In India, anaemia was associated with age, sex, caste, dietary diversity, and household hunger. Stunting was associated with age, sex, caste, wealth, and maternal illiteracy. Despite some basic shared factors, anaemia and stunting are more independent than commonly assumed. Interventions that target children based on 1 condition may miss children with the other form of malnutrition.