The adoption of healthful lifestyles by individuals and families can result in a reduction in many chronic diseases and conditions of which obesity is the most prevalent. Obesity prevention, in addition to treatment, is an important public health priority. This clinical report describes the rationale for pediatricians to be an integral part of the obesity-prevention effort. In addition, the 2012 Institute of Medicine report "Accelerating Progress in Obesity Prevention" includes health care providers as a crucial component of successful weight control. Research on obesity prevention in the pediatric care setting as well as evidence-informed practical approaches and targets for prevention are reviewed. Pediatricians should use a longitudinal, developmentally appropriate life-course approach to help identify children early on the path to obesity and base prevention efforts on family dynamics and reduction in high-risk dietary and activity behaviors. They should promote a diet free of sugar-sweetened beverages, of fewer foods with high caloric density, and of increased intake of fruits and vegetables. It is also important to promote a lifestyle with reduced sedentary behavior and with 60 minutes of daily moderate to vigorous physical activity. This report also identifies important gaps in evidence that need to be filled by future research.