In the conceptual definition of Stein et al,10 the term "functional limitations" refers to condition-related restrictions or impairments in age-appropriate function, activities, or social roles in the general areas of physical, cognitive, or emotional growth and development. The QuICCC domain of functional limitations includes 15 items (see Table 1). To operationalize this domain in this study, we selected NHIS-D variables that indicated whether the child was restricted in the type or amount of activities he or she could participate in; had a developmental delay (physical, mental, emotional/behavioral, or speech/language); or had difficulty in hearing, seeing, communicating, getting along with others, eating, dressing, bathing, or using the toilet. "Dependence on compensatory mechanisms" reflects the use of accommodations, devices, or personal assistance to compensate for or minimize a limitation in function, activity, or social role. The QuICCC has 12 items in this domain. We operationalized this domain using NHIS-D questions about use of regular prescription medicines; the need to avoid certain foods or to follow a doctor-ordered special diet; use of mobility, hearing, or visual aids; or the need for equipment and/or help from another person to feed oneself, dress, bathe, use the toilet, or perform other activities. Finally, service use or need beyond routine care for age includes 12 items specifying the use of or need for medical, psychological, or educational services beyond what is routine or usual for the child's age. For our analyses, the service use domain consisted of NHIS-D items that assessed overnight hospitalization, regular visits to their general practitioner or specialist, psychological counseling, physical or occupational therapy, other medical or nursing procedures, special classes or services at school, or home teaching.