To measure the effects of atopic dermatitis (AD) on the quality of life of affected young children and their families, we developed a prototype 62-item instrument, the Childhood Atopic Dermatitis Impact Scale (CADIS). The prototype CADIS was developed from a comprehensive conceptual framework based on data from parents and clinicians. The instrument had eight subscales (four each for child and parent): physical health, emotional health, physical functioning, and social functioning. The goal of this work was to test the validity of and to refine the prototype of CADIS. Two hundred seventy parents of children under the age of 6 y with AD responded to the instrument. Content validity was demonstrated by expert and parent reviews of the drafted and refined instrument, and by analyzing parents' responses to open-ended questions about their children's skin disease. Construct validity was assessed in exploratory factor analyses which supported a refinement in the conceptual framework to consist of two dimensions with five domains: child dimensions (symptoms and activity limitation/behavior), and parent dimensions (family/social function, sleep, and emotions). Seventeen items were eliminated, yielding a 45-item refined version of CADIS (score 0-180) with evidence of content and construct validity and suggested use in clinical research.