This systematic review of literature aimed to synthesize the multilevel factors related to physical activity (PA) among adults (age 18–65) with intellectual disability living in group homes. Keyword searches were used to identify articles from electronic databases, resulting in the inclusion of 10 articles for full-text review. Data were extracted relating to study and sample characteristics and study findings. Methodological quality of the studies was also evaluated. Factors related to PA in group homes were identified at all levels of the social–ecological model. Intrapersonal factors (e.g., health and functional status, attitude to PA), interpersonal factors (e.g., staff attitude, encouragement for PA, and coparticipation in PA), and organizational factors (e.g., program offerings, staff education, and staff–client ratios) were prominent findings in the reviewed studies. The findings support a social–ecological approach for PA promotion in group homes that target intrapersonal, interpersonal, and organizational factors.