Sport participation is associated with extensive positive developmental outcomes among typically developing youth (Fraser-Thomas et al., 2005); however, benefits may be even greater for youth with intellectual disabilities (ID) given unique physical and psychosocial considerations within this population (Hinckson et al., 2013). As such, this study examined factors associated with prolonged participation in and dropout from sport among youth with ID, using the Developmental Model of Sport Participation (DMSP; Côté & Fraser-Thomas, 2016) as a guiding framework of inquiry. Participants included 345 caregivers (81% mothers) of youth and young adult athletes with ID, recruited through Special Olympics (SO) Ontario. SO is a national sport organization, which aims to enrich the lives of individuals with ID through sport training and competitions. Caregivers completed an online survey in 2012, with provincial registry information from 2015 used to determine active athletes three years later. A multiple logistic regression analysis examined demographic, training, and psychosocial factors in relation to prolonged participation or dropout. Results showed a significant difference between those who dropped out and those who remained active, in terms of frequency of involvement. Specifically, those who participated in SO often (i.e., at least once per week) were nearly nine times more likely to stay involved than those who participated occasionally (i.e., less than once per week) (OR=8.82, 95% CI, 2.42-32.16). Findings are discussed within the context of previous sport development and ID literature, while implications for optimizing prolonged participation among youth with ID are explored.