OBJECTIVES:   Item response theory based computerized adaptive testing offers opportunity to measure health outcomes efficiently and economically.  The Cerebral Palsy Computer Adaptive Tests (CP-CATs) are parent-reported questionnaires developed to assess physical functioning in children and adolescents with CP. Concurrent validity and reliability of CP-CATs have already been established.  Prior to using them in research or clinical practice, it is important to examine their responsiveness as compared to the standard measure. The Pediatric Outcomes Data Collection Instrument (PODCI) is traditionally used to measure health and functional outcomes. Children and adolescents with CP often undergo musculoskeletal surgery to improve their functioning and health related quality of life (HRQOL), and therefore this serves as an apt paradigm to examine responsiveness of CP-CATs for activity, pain and global health with the corresponding PODCI measures. METHODS:   Ten sites across U.S. recruited patients two to twenty years of age who underwent musculoskeletal surgery between April 2009 and August 2013. Parents or other proxy respondents completed the CP-CATs and PODCI preoperatively and postoperatively at 6, 12 and 24 months. Change from baseline analyses at six months was performed for n=247-252, at twelve months for n=211-217 and at twenty-four months for n=120-123 subjects. Effect size (ES) and Standardized Response Mean (SRM) values were calculated for the CP-CATs and the comparable PODCI measures. RESULTS:   Overall, ES and SRM of CP-CATs for activity, pain and global health were significantly better than the corresponding PODCI measures for mobility, sports, pain and global health at 6 and 12 months.  At 24 months, CP-Activity CAT was more responsive than PODCI mobility and sports, and CP-Pain CAT’s responsiveness was similar to PODCI pain. CONCLUSIONS:   Results suggest that the CP-CATs may be more responsive to functional changes and HRQOL following musculoskeletal surgery in children and adolescents with CP, especially in the first 12 months post-surgery.