Aim: Participation in home, extracurricular, and community activities is a desired outcome of rehabilitation services for children and young people with cerebral palsy (CP). The purpose of this study was to investigate the effect of age and gross motor function on participation among children and young people with CP. Method: Five hundred participants (277 males, 223 females) were grouped by age and Gross Motor Function Classification System (GMFCS) level. There were 291 children aged 6 to 12 years and 209 young people aged 13 to 21 years. There were 128 participants in GMFCS level I, 220 in levels II/III, and 152 in levels IV/V. Participants completed the Children's Assessment of Participation and Enjoyment to measure number of activities (diversity) and how often they were performed (intensity) in the past 4 months. Results: Children had higher overall participation diversity and intensity than young people (p less than 0.001). Children and young people in GMFCS level I had the highest overall participation, followed by children and young people in levels II/III and IV/V. Children had higher participation in recreational (p less than 0.001) but not formal (such as team sports or clubs) or physical activities. Children (p less than 0.01) and young people (p less than 0.001) in level I had the highest participation in physical activities; diversity and intensity were generally low. Interpretation: The findings provide evidence of the effect of age and gross motor function on participation of children and young people with CP. Low participation in physical activities may have implications for fitness and health, especially for children and young people in GMFCS levels IV and V.