Children with developmental disabilities are at risk for limited participation in everyday activities. This study investigated factors that hindered or facilitated participation in 58 children with moderate-to-severe developmental disabilities who attended special schools. The parents completed surveys on their children's participation, developmental profile, environmental restrictions, parental self-efficacy and family demographics. Multiple regression analyses indicated that four variables were identified as strong predictors of specific children's participation and, overall, explained a small-to-moderate magnitude of variance. Social-emotional ability was associated positively with all aspects of children's participation (including diversity, intensity and enjoyment). Children with better communication and those who had only one sibling engaged in a higher number of activities and did so more frequently. The children of parents with higher self-efficacy enjoyed themselves more during participation. The findings provide preliminary information that could be useful for families and health care professionals to facilitate participation of children with moderate-to-severe developmental disabilities.