The prevalence of obesity in children and adolescents has increased dramatically in the past 3 decades. Childhood and adolescent obesity are associated with serious comorbidities including type 2 diabetes mellitus, hyperlipidemia, and hypertension. Most obese children and adolescents have no defined underlying endocrine or genetic syndrome. Evaluation of an obese child or adolescent involves a detailed personal and family history, physical examination, and selected laboratory evaluation. Lifestyle interventions and behavioral modification aimed at decreasing caloric intake and increasing caloric expenditure are essential to management of childhood and adolescent obesity. Surgical approaches have a role in management of morbid obesity and serious obesity-related comorbidities in adolescents. Further research is needed to evaluate the role of various dietary approaches and pharmacotherapy in the treatment of obesity in childhood and adolescence.