The purpose of this descriptive study was to quantify the work that is accomplished by major muscle groups of the affected limb of 10 children with spastic hemiplegia secondary to cerebral palsy during walking. Cinematographic film and force-plate data were used in a biomechanical link-segment model to calculate the positive and negative work performed by the muscles around each joint. The results revealed that the ankle plantar flexors produced just over a third of the positive work for the affected limb instead of the normal two thirds. The greatest proportion of positive work was performed by the hip muscles. More research using work and power analyses will assist in prescribing and determining the effectiveness of treatments.