Participation in home, school, and community activities is a primary outcome of early intervention services for children with disabilities and their families. The objectives of this study were to (a) describe participation of preschool-age children with cerebral palsy (CP); (b) determine effects of sex, age, and gross motor function on intensity of participation; and (c) identify child, family, and service determinants of intensity of participation. A convenience sample of 85 preschool-age children with CP and their parents participated. Parents completed self-report measures on children’s participation, adaptive behavior, physical function, family functioning, and services. Children’s Gross Motor Function Classification System levels (Palisano, Rosenbaum, Bartlett, & Livingston, 2008) were determined by assessors. A multiple linear regression analysis was conducted to determine the variance in intensity of participation explained by the determinants. Children with limited self-mobility had a lower intensity of participation than children with independent upright mobility. Adaptive behavior, transfers and basic mobility function, and upper extremity and physical function explained 46% of the variance of intensity of participation.