The present study used a population-based sample of children with cerebral palsy (CP) to estimate the prevalence of motor speech impairment and its association with activity and participation. A sample of 79 Victorian children aged 4 years 11 months to 6 years 5 months was recruited through the Victorian CP Register. The presence of motor speech impairment was recorded using the Viking Speech Scale (VSS). Activity and participation outcomes included speech intelligibility (the National Technical Institute for the Deaf rating scale, NTID), the Functional Communication Classification System (FCCS) and Communication Function Classification System (CFCS). A parent completed rating scale was used to examine the association between motor speech impairment and participation. Ninety per cent (71/79) of children demonstrated a motor speech impairment. Strong associations were found between the VSS and NTID (< .001), CFCS (< .001), and FCCS levels (<.001). VSS levels III–IV were significantly associated with restrictions in home, school, and community-based participation as perceived by parents. Although some diversity in activity and participation outcomes was observed within specific VSS levels, the results of this study suggested that children with mild motor speech impairments are more likely to demonstrate superior activity and participation outcomes compared to children with moderate or severe deficits.