Background The benefits of physical activity to maintain optimal health and well-being in children and adolescents are undisputed. The school environment offers opportuni- ties for children to be physically active. Objective The aim of this review is to systematically examine the effects of recess-based interventions on the physical activity (PA) levels of school-aged children and adolescents. Data Sources A systematic literature search was con- ducted to identify papers reporting interventions to pro- mote PA during school recess and/or lunchtime periods. The search was conducted in six databases (PubMed, SPORTDiscusTM, Web of Science, Proquest, Cochrane and Scopus) for papers published between January 2000 and April 2011. Study Selection Articles were included in the review if (i) they reported the findings of an intervention targeting PA levels of children and/or adolescents during school recess and/or lunchtime; (ii) have a measure of PA as an outcome variable; (iii) participants were aged between 5 and 18 years; and (iv) were published in English. Methods Two authors independently searched the litera- ture using the same search strategies to identify papers reporting interventions that promote PA during school recess and lunchtime periods. Methodological quality was assessed using an adapted eight item assessment scale. The effects of the interventions were assessed with a rating system used in a recent review of interventions in youth. Results The search originally retrieved 2,265 articles. Nine published peer-reviewed journal articles met the inclusion criteria for this review. Eight studies used ran- domized controlled trials and one was a controlled trial. Three studies demonstrated high methodological quality (33%). None of the studies adequately reported the ran- domization procedure or used power calculations. Few studies reported potential confounders and three studies had less than a 6 week follow-up. Five studies demon- strated a positive intervention effect on children's PA levels, with four reporting statistically significant increases and two reporting significant decreases in recess PA. The summary of the levels of evidence for intervention effects found inconclusive results for all intervention types, though promising strategies that require further investigation were identified. Limitations Whilst every effort was made to ensure that this review was as encompassing as possible, it may be limited by its search terms especially if there were studies with unclear titles or abstracts. In addition, only manu- scripts published in English were considered, eliminating any possible studies published in other languages. Conclusions All of the studies used an objective measure to assess PA outcomes, although several criteria were consistently absent from the studies. The levels of evidence were not sufficient to establish conclusive intervention effects on children's recess PA. This could be due to the small number of published studies. There is a need for higher-quality intervention research to strengthen pub- lished findings to inform recess PA interventions. Inter- vention research is needed in adolescents due to the absence of school recess intervention research in this population.