Population-based, 'whole of community' interventions utilise community engagement processes and implement multiple strategies to improve the health of populations defined by geographical boundaries (i.e. cities, villages or regions). The aim of the review was to systematically assess the current state of knowledge about the effectiveness of population-based whole of community interventions in preventing excessive population weight gain. Systematic searches of electronic databases (1990-2011) and reference lists of included trials and previous reviews were conducted to identify interventions to prevent excessive weight gain. Population-based, whole of community interventions were defined as those targeting the weight status of a population characterised along geographical boundaries. The review included eight trials. All of the identified trials targeted children or adolescents. Seven trials reported a significant effect favouring the intervention on at least one measure of adiposity. Meta-analysis of six trials revealed a small reduction in BMI z-score among participants in intervention communities (mean difference (MD) -0.09; 95% confidence interval (CI) -0.16 to -0.02). The review suggests that population-based, whole of community interventions can be effective in achieving modest reductions in population weight gain among children.