PURPOSE: The purpose of this study was to investigate changes in endurance, strength, function, and self-perception before, during, and after aerobic exercise intervention in three ambulatory adolescents with spastic cerebral palsy. METHODS: Three individuals (17-20 years of age) with spastic cerebral palsy participated. An A1B1A2B2 design was employed. Data obtained during the different phases included energy expenditure index (EEI), lower extremity muscle strength using a handheld dynamometer, the Gross Motor Function Measure (GMFM), and the Self-Perception Profile for College Students (SPPCS). RESULTS: All participants had a significant improvement in at least one of the components of the EEI. Combined mean strength of quadriceps, hamstrings, and ankle plantarflexors and dorsiflexors increased bilaterally for all participants. Gross motor function improved for all participants in at least one phase of the study. The self-perception of appearance improved for all participants. CONCLUSIONS: Aerobic exercise may help increase strength of the lower extremity muscles, decrease energy required to ambulate, and improve gross motor function and self-perception for some adolescents with spastic cerebral palsy.