We contrasted Behavior Assessment System for Children, Second Edition--Parent Rating Scales--Preschool Form (BASC-2 PRS-P) parent ratings for 242 (52% African American; 39% White) preschool-aged children from three diagnostic groups: autism spectrum disorder (ASD), intellectual disability (ID), and ASD and ID (ASD/ID). Across diagnostic groups, atypical behavior, attention, and adaptive functioning were rated as problematic; Developmental Social Disorders (DSD) scores were elevated across diagnostic groups and did not differ. Several BASC-2 clinical and adaptive scales differed across diagnostic groups, with parent-rated aggression higher for the ID group, parent-rated social withdrawal higher for the ASD group, and parent-rated social skills lower for the ASD/ID group. No differences in BASC-2 scores were found across African American and White preschoolers. The BASC-2 identified problem areas in a preschool clinical sample that were consistent with those of preschoolers with developmental disabilities. However, findings did not support use of the DSD as an ASD-specific screening measure.