Our purpose was to estimate national population prevalence rates of functional limitations in children ages 5-17 years. We developed a methodology for measuring severity of mobility, self-care, communication and learning ability using the 1994 National Health Interview Survey-Disability Supplement (NHIS-D). NHIS-D included 45,705 households, involving 116,179 people of whom 21,415 were children. Our framework for analysis included the National Centers of Medical Rehabilitation Research (NCMRR) framework of pathophysiology, impairment, fucntional limitations, disability, and handicap. We used categories from the Pediatric Functional Independence Measure(WeeFIM®) to clarify functional limitations in self-care/continency, mobility-locomotion, communication, and social-cognitive/learning skills. Sociodemographic risk factors included race, household structure, education of adult caretaker, and family income. Activity limitation included no limits, non-school limits, school limits and unable to attend school. Perceived disability included parents and health-community professional feedback. Activity limitations were present in 9% and perceived disability in 3.4%. Mobility limitations were evident in 1.3%, self-care limitations in 0.9%, communication limitations in 5.5% and learning limitations were found in 10.6% of the sample. Overall, 12.3%of school age children have some functional limitations (minor 4.2%, severe 8.1%). OLS multivariate models were used to predict activity limitation and perceivd disability. WeeFIM categories accounted for 30% of activity limitations and 46% of perceived disability variance. Sociodemographic differences were significant between age groups in self-care and communication. There were significant differences between blacks, whites, and hispanics in communication and learning ability. Family structure, education of mother and family income had significant impacts on self-care, communication and learning ability limitations. Ordered logistic regression demonstrated strong significant impact on functional limitations for family structure, mothers education and family income. We conclude that the NHIS-D is an excellent population based system for examining functional limitations in school age children.