To test the Child Behavior Checklist's (CBCL/1½-5) ability to screen for autism spectrum disorders (ASD), we studied Korean preschoolers: 46 with ASD, 111 with developmental delay (DD), 71 with other psychiatric disorders (OPD), and 228 non-referred (NR). The ASD group scored significantly higher than the other groups on the Withdrawn and DSM-Pervasive Developmental Problems (DSM-PDP) scales as well as attaining higher scores (p < 0.001) on seven items reflecting ASD. With a T = 65 cutpoint on the DSM-PDP scale, sensitivity was 80% for identifying ASD relative to the other three groups, but specificity varied across groups: NR = 87%, OPD = 55%, DD = 60%, replicating in a non-Western sample results from previous studies. Results suggested that the CBCL/1½-5 performs best in Level 1 screening, namely differentiating children with ASD from children in the general population.