This review characterizes physical activity behavior in youth with intellectual disability (ID) and identifies limitations in the published research. Keyword searches were used to identify articles from MEDLINE, EBSCOhost Research Databases, Psych Articles, Health Source, and SPORT Discus, and ProQuest Dissertations and Theses up to June 2007. Data were extracted from each study using a template of key items that included participant population, study design, data source, and outcome measure. Nineteen manuscripts met the inclusion criteria. Findings were mixed, with various studies indicating that youth with ID have lower, similar, and higher physical activity levels than peers without disabilities. Only two studies provided enough information to determine that some youth with ID were meeting minimum physical activity standards. Significant methodological limitations prohibit clear conclusions regarding physical activity in youth with ID. (Contains 1 table.)