Ethnicity is associated with differences in food-related beliefs, preferences, and behaviors, and cultural influences may contribute to the higher than average risk of obesity among children and youth in U.S. ethnic minority populations. However, cultural attitudes and beliefs are not the only potential source of ethnic variation in childhood obesity prevalence and should not be studied in isolation. Demographic, socio-structural, and environmental variables must also be considered. Available evidence indicates ethnic differences along several pathways that may increase risks of obesity development during gestation, infancy, childhood and adolescence. These include above-average prevalence of obesity in adult females and of maternal diabetes during pregnancy, parental attitudes and practices that may lead to overfeeding children, above-average levels of consumption of certain high calorie foods and beverages, and inadequate physical activity. Environments with lower than average neighborhood availability of healthful foods and higher than average availability of fast food restaurants, along with exposure to ethnically targeted food marketing may contribute to reliance on high calorie foods and beverages, and these foods may be socially and culturally valued. Attitudes about and environmental contexts for physical activity are also relevant. Increasingly, it is acknowledged that individual behaviors and lifestyles, e.g. food choices or child feeding practices, are responsive to the ecological contexts in which they are practiced. Focusing attention on the fluid interactions of cultural influences with contextual factors, of recognized importance for the study of childhood undernutrition, can also lead to further understanding of how to address ethnic disparities in childhood obesity.