Objectives. To translate, cross-culturally adapt, and validate the functional disability tool Childhood Health Assessment Questionnaire (CHAQ), a variant of the Health Assessment Questionnaire (HAQ), in children with juvenile idiopathic arthritis (JIA). Children and methods. The disability index is the mean of the scores on the eight domains of the CHAQ and can range from 0 (no disability) to 3 (maximum disability). The CHAQ was first translated into French and adapted, then validated in a multicenter cross-sectional study in 306 children with JIA (systemic onset, 23%; polyarticular onset, 22%; extended oligoarticular subtype, 25%; and persistent oligoarticular subtype, 30%). Results. Overall CHAQ scores discriminated between the four JIA subtypes (systemic: 1.1 ± 0.9; polyarticular: 0.8 ± 0.7, extended oligoarticular: 0.8 ± 0.7, and persistent oligoarticular: 0.4 ± 0.5 P < 0.0001 ). Reproducibility evaluated by test-retest at a 7-day interval was excellent (intraclass coefficient, 0.91), as was agreement between the Parent's and Children's versions of the questionnaire (intraclass coefficient, 0.89). Significant correlations were found between the overall CHAQ score and variables reflecting disease severity (joint counts, physician's and parent's global assessments, and erythrocyte sedimentation rate), indicating excellent convergent validity of the tool. Conclusions. The French version of the CHAQ displays good psychometric characteristics, although its sensitivity to change remains to be established. The French version of the CHAQ should prove useful in international studies and can be expected to be helpful for monitoring individual patients with JIA.