Authors contrasted Bracken Basic Concept Scale: Receptive, Third Edition (BBCS: R-3) test performance between 57 children with intellectual disability (ID) and 76 children with autism spectrum disorder (ASD) and ID. BBCS: R-3 School Readiness Composite (SRC) and Self-/Social Awareness subtests were analyzed. Multivariate analysis of covariance revealed no differences between groups on SRC performance; however, children with ID demonstrated better mastery of self-/social awareness concepts when compared to children with ASD. Within the group of children with ASD, mastery of school-based concepts exceeded mastery of self-/social awareness concepts. Findings suggest relatively greater delays in mastery of self-/social awareness concepts for young children with ASDs when compared to mastery of other concepts.