Childhood obesity is highly prevalent in the U.S. and has become a global epidemic. The 2007-2008 National Health and Nutrition Examination Survey data showed that 17% of U.S. children and adolescents (ages 2-19) years were obese, and over 30% were overweight or obese. Childhood obesity leads to obesity in adulthood and many other serious health conditions, such as cardiovascular, metabolic, and psychosocial illnesses. To assess the effectiveness of existing childhood obesity prevention efforts, the Johns Hopkins University Evidence-based Practice Center completed a systematic review on childhood obesity prevention studies conducted in high-income countries. This report systematically reviewed seven key questions: What is the comparative effectiveness of school-based interventions for the prevention of obesity or overweight in children? What is the comparative effectiveness of home-based interventions for the prevention of obesity or overweight in children? What is the comparative effectiveness of primary care-based interventions for the prevention of obesity or overweight in children? What is the comparative effectiveness of childcare setting-based interventions for the prevention of obesity or overweight in children? What is the comparative effectiveness of community-based or environment-level interventions for the prevention of obesity or overweight in children? What is the comparative effectiveness of consumer health informatics applications for the prevention of obesity or overweight in children? What is the comparative effectiveness of multi-setting interventions for the prevention of obesity or overweight in children? Though the strength of evidence is moderate to high for school-based interventions, the limited number of studies and insufficient or low strength of evidence to support interventions in other settings made it difficult to conclude that interventions in other settings could effectively prevent childhood obesity. Based on the evidence gaps in these settings, we identified the following as Future Research Needs: Future research is needed on interventions delivered in settings other than schools or home. While there have been other reviews on the effectiveness of interventions on food and nutrition policies at school on changes in children's diet and school food environments, there are still gaps in the literature on some aspects, such as the impact of regulations on food availability and its impact on obesity prevention. Only a few studies that we reviewed used social marketing to deliver messages on nutrition, physical activity and health. This approach might be integrated with other intervention components to create an atmosphere favorable to healthy and active lifestyles and related behavioral changes. Further testing of the value of consumer health informatics products for obesity prevention is needed. In addition, there is a lack of evidence on the impact of regional or national policies on childhood obesity prevention. Further research might be conducted with stratified analyses on subgroups, such as by gender, age, race/ethnicity, or socioeconomic status. There were methodological limitations of the reviewed studies which suggest that future research might improve upon the methods. Few of the studies we reviewed reported process evaluation, which would provide useful insight regarding why some studies might detect desirable effect of the intervention. Future studies need to design innovative approaches that have a high likelihood of sustainability. This may be designed to take advantage of other existing public health, government or other organization supported programs or try to gain more support and engagement from related key stakeholders. The objective of this report is to prioritize the needs for research addressing gaps in the existing literature on the effectiveness of childhood obesity prevention programs by engaging expert stakeholders using a modified Delphi method.