Authors reviewed randomly controlled studies of universal prevention of childhood obesity, identifying 29 studies that met review criteria. Review suggested that outcomes are generally modest across all age groups and there were few replications of any program; thus, at this time no universal prevention program for childhood obesity meets criteria for a well-established intervention of the American Psychological Association. A wide variety of intervention targets have been investigated (knowledge and attitudes, family involvement, physical activity, television watching, water consumption, vegetable consumption, breast feeding, etc.) in a wide number of countries. Effects seem to be stronger for girls than for boys, for unknown reasons. Many studies fail to achieve sufficient statistical power and/or a sophisticated measurement strategy, neglecting key variables such as cost, treatment fidelity, longer-term follow up data, and process variables. Questions as to the theories of change associated with the interventions are also raised and suggestions for future research in this area are provided.