Computer-based analysis of gait was used to study walking and running in 19 children with spastic-diplegic cerebral palsy (CP) and 15 healthy control children. Temporospatial parameters, kinematic and kinetic data were compared and contrasted between groups for both types of gait. The majority of children with diplegic CP, who are independent ambulators, are able to run. These children increase their velocity by increasing their cadence, a mechanism that is distinct (and presumably less energy efficient) from that used by healthy children. Sagittal-plane kinematic and kinetic profiles at the ankle in children with CP were more similar to normal profiles in running than in walking, suggesting that the primary deviations at the ankle associated with CP are better tolerated at greater velocities. Relative power analysis showed that, like healthy children, those with CP depend more upon the proximal musculature about the hip for power generation as the velocity of gait increases. Children with CP achieve energy transfer between adjacent joints during walking and running in a manner comparable to unaffected children. Running is an important activity for children and should be considered in the functional assessment of those with CP.