To examine the effectiveness of intensive interdisciplinary pain treatment for improving disability in children with chronic headache using the International Classification of Functioning, Disability and Health model as a conceptual framework for disability assessment. Children with chronic headache ( = 50; ages 10-19 years; 62% female) attended an intensive interdisciplinary pain treatment program 8 h/day, 5 times/week for 2-7 weeks. Disability measures were administered at admission, discharge, and 6-8 week follow-up. Disability outcomes were analyzed retrospectively. Wilcoxon signed rank tests and Friedman's analyses of variance were used to compare scores across two and three longitudinal time points, respectively. After rehabilitation, disability reduced on the Headache Impact Test-6 from severe impact at admission to some impact at follow-up ( < 0.001). Median time on the modified Bruce protocol increased from 13.1 min (interquartile range = 12.6-14.1) to 14.4 min (interquartile range = 12.9-16.3), < 0.001, with gains maintained at follow-up. Improvements in pain and disability were associated with improvements in school participation. Findings of this study support the effectiveness of intensive interdisciplinary pain treatment for improving disability in children with chronic headache.Implication for rehabilitationIntensive interdisciplinary pain treatment is effective for improving pain and disability in children with chronic headaches.Application of the ICF model to disability assessment suggests that children with chronic headaches may experience significant disability, even when standardized assessments of physical capacity are normal.The modified Bruce protocol, Pediatric Evaluation of Disability Inventory – Computerized Adaptive Tests, and Headache Impact Test-6 appear particularly valuable in understanding the nature of disability in children with chronic headaches.