Aims: To investigate associations between functioning, community participation, and quality of life (QoL) and identify whether participation mediates the effects of functioning on QoL. Method: The caregivers of 435 children (211 females, 224 males; mean age 12y; SD 3y 11mo; age range 5–18y) with intellectual disability and autism spectrum disorder, cerebral palsy, Down syndrome, or Rett syndrome reported on their child’s functioning (dependence for managing personal needs, mobility, communication, eye contact when speaking), frequency of participation, and QoL. Linear regression and mediation analyses were used to evaluate the relationships between child functioning, participation, and QoL. Results: Children with greater dependency for managing personal needs and limited eye contact when speaking experienced poorer QoL. Less impaired functioning was associated with more frequent participation, which, in turn, was associated with a 3-point gain in QoL for each additional point in frequency of participation (coefficient=2.67, 95% confidence interval 1.56–3.78). The effect of impaired functioning on QoL was partially mediated by participation in children with greater dependency in managing personal needs and those with mildly impaired communication. Interpretation: Greater levels of impairments with poorer functioning, notably a high level of dependence, were associated with poorer QoL. Poorer QoL can be partly explained by less frequent community participation.