A multivariate model of determinants of change in gross-motor ability and engagement in self-care and play provides physical and occupational therapists a framework for decisions on interventions and supports for young children with cerebral palsy and their families. Aspects of the child, family ecology, and rehabilitation and community services may influence children's activity and participation. Aspects of the child include primary and secondary impairments, associated and comorbid health conditions, and adaptive behaviors. Literature support for the model is reviewed. A clinical scenario illustrates the use of the model as a framework for practice. The model encourages therapists to broaden the focus of rehabilitation services for young children with CP to include not only development of motor abilities but also comprehensive interventions and supports to enhance participation in daily activities and routines. Therapists are encouraged to consider how child, family, and service factors interact when planning interventions and evaluating outcomes. (Contains 1 figure.)