Parents are often concerned about their child's development, but it is unknown whether concerns indicate actual developmental problems. Pilot studies within 96 families showed that parents' concerns about their children's development took the form of value judgments, could be classified into commonly accepted developmental domains, and related to performance on screening tests. In our study, 100 families seeking pediatric care were asked to list any concerns about their child's development while their children received developmental screening. Eighty percent of the children who failed screening had parents with concerns about articulation, language, fine-motor skills, or global development. Ninety-four percent of the children who passed screening had parents with no concerns or concerns in other developmental areas. The types of concerns parents raised did not vary significantly with level of education, experience in child rearing, or other demographic variables. These results suggest that parental concerns may be a helpful adjunct to standardized developmental screening.