This study investigates the language functioning of 89 children diagnosed with autism using standardized language tests. The findings reveal significant heterogeneity in language skills among these children, with some having normal language skills and others showing significantly below-average language abilities. The profile of language-impaired children with autism is similar to that of children with specific language impairment (SLI), suggesting potential genetic overlap between autism and SLI. The study also highlights the importance of considering both receptive and expressive language abilities, finding no significant differences between them in vocabulary knowledge. Additionally, the study examines the relationship between IQ and language abilities, noting that higher IQ scores are associated with better language skills. The results suggest that language skills can be independent of IQ in autism, and that articulation skills are generally spared in this population. The findings have implications for understanding the genetics and definition of both autism and SLI, and call for further research to explore the neurocognitive mechanisms underlying language processing in these disorders.This study investigates the language functioning of 89 children diagnosed with autism using standardized language tests. The findings reveal significant heterogeneity in language skills among these children, with some having normal language skills and others showing significantly below-average language abilities. The profile of language-impaired children with autism is similar to that of children with specific language impairment (SLI), suggesting potential genetic overlap between autism and SLI. The study also highlights the importance of considering both receptive and expressive language abilities, finding no significant differences between them in vocabulary knowledge. Additionally, the study examines the relationship between IQ and language abilities, noting that higher IQ scores are associated with better language skills. The results suggest that language skills can be independent of IQ in autism, and that articulation skills are generally spared in this population. The findings have implications for understanding the genetics and definition of both autism and SLI, and call for further research to explore the neurocognitive mechanisms underlying language processing in these disorders.