Maternal decisions about breastfeeding (BF), formula feeding, and complementary feeding are guided by biological and socio-cultural factors. Obese women often experience poor BF outcomes. Maternal weight is also a proxy for the food environment because diet is a determinant of weight. Our understanding of cultural knowledge and the mother-child food relationship in complementary feeding remain fragmentary. The aims of this dissertation were to examine the association between maternal fatness and child feeding practices from 0-24 mo and understand conceptualizations and practices of child feeding, particularly the mother-child food relationship within the household food environment. First we examined if maternal fatness was associated with BF duration, dietary diversity (DD), and child feeding index (CFI), using data from Mexican mother-child pairs. Maternal fatness was not associated with BF duration or DD. Maternal fatness was not a significant factor in CFI as measured by the index. Second, ethnography was used to examine how 31 mothers in Xoxocotla, Morelos, Mexico conceptualized complementary feeding practices. The eight concepts identified were: probaditas, preparing separate foods, readiness to eat solid foods, consistency, variety, child likes and dislikes, money and food costs, and healthiness of foods. There was strong evidence of cultural consensus. Household factors influenced feeding practices. Last, data from 24-h recalls of 25 mother-child pairs (9-18 mo-old) from the ethnographic study were used to examine the maternal-child food relationship and the household food environment. The frequency of shared meals and foods between mother and child was attributable to maternal concepts of child foods, time of day, the child's age and sleep patterns, family and maternal food preferences, maternal social roles, and presence of family members at meals. This complexity was captured by the maternal and child food space concept. This dissertation showed that maternal fatness was not of public health significance in child feeding, whereas maternal knowledge and household food environment were important. The ethnographic findings have implications for how we approach child feeding, such that to improve practices we must use the maternal system of knowledge and consider the social processes that construct the complementary diet beyond educating mothers on food quality and consistency.