Abnormalities of growth and development are prevalent in children with cerebral palsy (CP). The purpose of this study was to assess skeletal maturation ('bone age') in this population and to identify those factors related to alterations in this aspect of development. The study group was a convenience sample of 80 participants (47 males, 33 females; age range 2y 6mo to 21y 1mo; mean age 10y 10mo, SD 4y 2mo). All had moderate to severe spastic or mixed spastic CP at Gross Motor Function Classification System level III (n=8, 10%); level IV (n=21, 26%); or level V (n=51, 64%). Skeletal maturation was assessed by the detailed Fels method of scoring hand-wrist radiographs. Each evaluation included clinical and anthropometric assessments, Tanner staging, bone density measurements, and the Children's Health Status Questionnaire. Follow-up evaluations were obtained for 41 participants, providing a total of 143 evaluations. Median interval between first and last evaluations was 24.7 months (range 11.9 to 45mo). For the study group as a whole there was no significant difference between a child's skeletal age and chronological age. However, there was a high prevalence of individual participants in whom skeletal age was advanced (7%) or delayed (10%), relative to chronological age, by more than 2 years. In multivariant analyses it was found that diminished linear growth (height), low lumbar-spine bone density, and low body fat as measured by triceps skinfolds were all independently associated with delays in skeletal maturation. Multiple aspects of skeletal growth and development, including skeletal maturation, are frequently altered in children with moderate to severe CP.