Purpose The purpose of this scoping review was to determine the health-equity issues that relate to childhood obesity. Methods Health-equity issues related to childhood obesity were identified by analyzing food environment, natural and built environment, and social environment. The authors searched Medline, PubMed, and Web of Science, using the keywords “children” and “obesity.” Specific terms for each environment were added: “food desert,” “advertising,” “insecurity,” “price,” “processing,” “trade,” and “school” for food environment; “urban design,” “land use,” “transportation mode,” “public facilities,” and “market access” for natural and built environment; and “financial capacity/poverty,” “living conditions,” “transport access,” “remoteness,” “social support,” “social cohesion,” “working practices,” “eating habits,” “time,” and “social norms” for social environment. Inclusion criteria were studies or reports with populations under age 12, conducted in the United States, and published in English in 2005 or later. Results The final search yielded 39 references (16 for food environment, 11 for built environment, and 12 for social environment). Most food-environment elements were associated with obesity, except food insecurity and food deserts. A natural and built environment that hinders access to physical activity resources and access to healthy foods increased the risk of childhood obesity. Similarly, a negative social environment was associated with childhood obesity. More research is needed on the effects of food production, living conditions, time for shopping, and exercise, as related to childhood obesity. Conclusions Most elements of food, natural and built, and social-environments were associated with weight in children under age 12, except food insecurity and food deserts.