Few tools are available to pediatricians for tracking and monitoring disability status in children. We describe the conceptual basis and pilot use of the Functional Independence Measure for Children (WeeFIM). Our pilot use of this instrument in children with limb deficiency, Down's syndrome, spina bifida, cerebral palsy, and extreme prematurity demonstrates that the WeeFIM is a valid measure for tracking disability in preschool age and middle childhood. The WeeFIM measures the impact of developmental strengths and difficulties on independence at home, in school, and in the community. This allows the pediatrician to prioritize interventions for enhancing comprehensive functional outcomes and supporting families.