Few studies examine the clinical utility of autism spectrum disorder (ASD) rating scales for screening referrals to child psychiatry clinics. Parents/teachers from Long Island, NY, completed the Child Symptom Inventory-4, a DSM-IV-referenced rating scale for 6- to 12-year-old clinical referrals with an ASD (N = 317) or nonASD psychiatric (N = 191) diagnosis. Two separate groups of children attending public school, regular education classes in the same geographic area were also rated by their parents (N = 446) and teachers (N = 464). Stepwise forward regression generated a scoring algorithm based on a subset of all CSI-4 items that best differentiated ASD from nonASD children. ROC analyses indicated high levels of sensitivity/specificity for recommended ASD cutoff scores for parent and teacher ratings.