The purpose of this article was to review population-based interventions for preventing childhood obesity carried out in school settings published between 1999 and 2004. A total of 11 such interventions were found from USA and UK. The grade of the interventions was from kindergarten, primary grades, middle school to high school. Most of these interventions targeted both physical activity and nutrition behaviours although there were some interventions that focused on only one dimension such as TV watching or restricting drinking of carbonated drinks or increasing physical education time in the school. Most of the interventions were based on some behavioural theory and the most popular theory was social cognitive theory. Most of the interventions focused on individual level behaviour change approaches. Most of the interventions focused on short-term changes right after the intervention. On the whole, interventions resulted in modest changes in behaviours and mixed results with indicators of obesity. TV watching seems to be most modifiable behaviour, followed by physical activity and nutrition behaviours. The outcome measures such as lowered BMI (body mass index), triceps skin-fold thickness and waist circumference have not been measured by all studies. Recommendations for enhancing the effectiveness of school-based childhood obesity interventions are presented.