This article reviews the epidemiology, differential diagnosis, predisposing factors, and therapeutic interventions for pediatric obesity. The prevalence of childhood obesity is increasing as a result of the interaction between a strong genetic predisposition that facilitates storage of fat, and environmental influences, including the easy access to calorically-dense foods and the low levels of physical activity that characterize modern societies. Mental health care professionals must frequently address pediatric obesity not only because of its rising prevalence in the general population, but also because a number of pharmacotherapies used to treat psychological disorders appear to increase body weight. Childhood obesity has pervasive psychosocial and medical consequences, both in the short and the long-term.