A disability assessment tool, the Juvenile Arthritis Functional Assessment Scale, was developed for, and validated in, patients with juvenile rheumatoid arthritis (JRA). Standards for this 10-item tool were developed using the scores of 63 normal school children as controls and comparing these results with those of 71 age-matched JRA patients (age 7-16 years). The JRA patients scored statistically significantly higher on the scale, which also demonstrated excellent internal and convergent validity and internal reliability. The test is easily administered in 10 minutes by a physical or occupational therapist in a clinical or office setting. This tool represents the first normalized disability assessment tool developed for JRA patients.