Childhood and adolescent obesity has increased dramatically during the past 30 years and now represents one of the most pressing national and international public health priorities. During the early 1970s, 3 to 6 percent of American children and adolescents were obese. By 2004, this number had increased five fold to 16 to 18 percent of all US 6 to 19 year olds. This increase is especially troubling as obese children and adolescents have a greater risk for adult obesity, with its attendant health risks, and may experience obesity-related health conditions before adulthood, including type 2 diabetes mellitus, fatty liver disease, and elevated cardiovascular risk factors. Severe obesity in children and adolescents can be associated with severe health consequences and dire impacts on quality of life. The true toll of childhood obesity must be calculated across the lifespan since it often continues into adulthood. Thus, an important step to preventing adult obesity and its related health consequences is effectively treating childhood obesity. To this end, we conducted this systematic review to determine which treatments could effectively address child and adolescent obesity and overweight, including behavioral, pharmacological, and surgical treatment options. In conjunction with a Technical Expert Panel, we developed a set of five key research questions to evaluate the effectiveness and safety of behavioral, pharmacological, and surgical treatments for obese and overweight children and adolescents who were 2 to 18 years old. These research questions addressed various measures of the health impact of treatments to reduce or stabilize weight, including: short-term impacts on weight control (6 to12 months after enrolling in treatment); maintenance of weight changes in the medium-term (between 1 to 5 years after enrollment) or longer-term (5 or more years after enrollment); adverse effects of treatment (immediate and over time); beneficial effects of treatment, aside from weight control or weight loss; and treatment components or other factors that influence the effectiveness of treatments.