We analyzed CBCL/1½-5 Pervasive Developmental Problems (DSM-PDP) scores in 3- to 5-year-olds from the Study to Explore Early Development (SEED), a multi-site case control study, with the objective to discriminate children with ASD (N = 656) from children with Developmental Delay (DD) (N = 646), children with Developmental Delay (DD) plus ASD features (DD-AF) (N = 284), and population controls (POP) (N = 827). ASD diagnosis was confirmed with the ADOS and ADI-R. With a cut-point of T = 65, sensitivity was 80% for ASD, with specificity varying across groups: POP (0.93), DD-noAF (0.85), and DD-AF (0.50). One-way ANOVA yielded a large group effect (?[superscript 2] = 0.50). Our results support the CBCL/1½-5's as a time-efficient ASD screener for identifying preschoolers needing further evaluation.