The assessment of children's health status presents unique difficulties. These include parent-child differences in reports of functioning, knowledge of what constitutes age-appropriate functioning, obtainment of accurate information for child, and demonstration of the predictivity of health status measures. Recent measures (the Functional Status II-R and instruments from the RAND Health Insurance Experiment) address physical, social, and psychologic domains of children's health. The authors modified these instruments to develop short (7 and 14 items) questionnaires (RAND, FSQ) to assess child health. Scoring on these questionnaires was compared with traditional measures of illness severity and medical service utilization. The authors also evaluated coding illness-specific and general health limitations (FSQ-S and FSQ-G, respectively). Patients included the parents of 113 children with chronic illness (100 asthmatics). Measure stability was evaluated over a 6-month period in a subset of patients. Internal consistency (Cronbach's alpha) of the seven-item RAND measure was .78, the FSQ-S .78, and the FSQ-G .73 to .89 during repeated samplings over 6 months. The FSQ-S and Rand seven-item measure were moderately correlated (.47, P less than .001). The authors observed significant correlations among alternate codings of the FSQ and RAND and between the FSQ-S, FSQ-G, RAND, and severity measure with traditional indices of medical service utilization. Parents were more likely to attribute certain functional status problems (e.g., being tired) to illness than they were other problems (e.g., moodiness or interest in things). The findings demonstrate that these measures have acceptable psychometric properties and provide preliminary evidence of construct validity in a group of young children with asthma. Using general and specific measures will provide differing pictures of a child's functioning. No single measure completely taps the impact of illness as measured by a panel of traditional indicators of illness burden and medical service utilization.