Investigators developed a review system to evaluate the growing literature on policy and environmental strategies to prevent childhood obesity. More than 2000 documents published between January 2000 and May 2009 in the scientific and grey literature were identified (2008–2009) and systematically analyzed (2009–2012). These focused on policy or environmental strategies to reduce obesity/overweight, increase physical activity, and/or improve nutrition/diet among youth (aged 3–18 years). Guided by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) framework, investigators abstracted studies of 24 intervention strategies and assessed evidence for their effectiveness (i.e., study design, intervention duration, and outcomes) and population impact (i.e., effectiveness and reach—participation or exposure, and representativeness) in 142 evaluation study groupings and 254 associational study groupings (n=396 groupings of 600 peer-reviewed studies).