The Pediatric Symptom Checklist (PSC) is a 35-item screening questionnaire that is completed by parents and designed to help pediatricians in outpatient practice identify school-age children with difficulties in psychosocial functioning. The current study assessed the validity of the PSC by screening 300 children in two pediatric practices, a middle-class group practice and an urban health maintenance organization. Validity was established by comparing the results of PSC screening of 48 children with in-depth interview assessments and pediatricians' ratings. Results indicate that the PSC has a specificity of 0.68 and a sensitivity of 0.95. The screening process was well accepted by parents and pediatricians. Several children whose pediatricians' ratings had indicated adequate functioning were identified by the PSC as having substantial psychosocial dysfunction and requiring further evaluation.