OBJECTIVE: To examine score agreement, validity, precision, and response burden of a prototype computer adaptive testing (CAT) version of the self-care and social function scales of the Pediatric Evaluation of Disability Inventory compared with the full-length version of these scales. DESIGN: Computer simulation analysis of cross-sectional and longitudinal retrospective data; cross-sectional prospective study. SETTING: Pediatric rehabilitation hospital, including inpatient acute rehabilitation, day school program, outpatient clinics; community-based day care, preschool, and children's homes. PARTICIPANTS: Children with disabilities (n=469) and 412 children with no disabilities (analytic sample); 38 children with disabilities and 35 children without disabilities (cross-validation sample). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Summary scores from prototype CAT applications of each scale using 15-, 10-, and 5-item stopping rules; scores from the full-length self-care and social function scales; time (in seconds) to complete assessments and respondent ratings of burden. RESULTS: Scores from both computer simulations and field administration of the prototype CATs were highly consistent with scores from full-length administration (r range, .94-.99). Using computer simulation of retrospective data, discriminant validity, and sensitivity to change of the CATs closely approximated that of the full-length scales, especially when the 15- and 10-item stopping rules were applied. In the cross-validation study the time to administer both CATs was 4 minutes, compared with over 16 minutes to complete the full-length scales. CONCLUSIONS: Self-care and social function score estimates from CAT administration are highly comparable with those obtained from full-length scale administration, with small losses in validity and precision and substantial decreases in administration time.