We sought to determine whether interventions that emphasize decreasing sedentary behaviours in children and adolescents result in behaviour change and weight control. A comprehensive literature search was conducted to identify all comparative studies of interventions to reduce sedentary behaviour among children, alone or in combination with other health messages. Two investigators evaluated articles for eligibility and validity. As methods, settings and interventions differ across studies, results were synthesized narratively. Twelve studies met the inclusion criteria and provided relevant data. Six targeted clinic-based populations that were overweight or at risk of overweight, and six were population-based prevention studies. Approaches varied, but all reduced sedentary behaviour and improved weight indices. An emphasis on decreasing sedentary behaviours is an effective intervention to decrease sedentary behaviours and control weight in children and adolescents.