Children with autism were compared to children with Down syndrome and typically developing children in terms of their ability to visually orient to social and nonsocial stimuli and their ability to share attention. Children with autism were more likely to fail to orient to all stimuli, with social stimuli being particularly challenging. They also took longer to orient to social stimuli and showed impairments in shared attention. Correlational analyses revealed that shared attention performance was related to the ability to orient to social stimuli, but not to nonsocial stimuli. These findings suggest that social orienting impairments may contribute to difficulties in shared attention in autism. The study used a naturalistic approach to examine social attention in young children with autism, which could be useful in clinical assessments. The participants included 20 children with autism or PDDNOS, 19 with Down syndrome, and 20 with typical development. Diagnoses were based on parent interviews and structured play sessions. Children with autism had higher nonverbal ability compared to those with Down syndrome and typically developing children. The study aimed to determine whether children with autism selectively failed to orient to social stimuli compared to nonsocial stimuli and whether impairments in social orienting were related to impairments in shared attention. The results support the hypothesis that difficulties in orienting to social stimuli may contribute to difficulties in shared attention in autism.Children with autism were compared to children with Down syndrome and typically developing children in terms of their ability to visually orient to social and nonsocial stimuli and their ability to share attention. Children with autism were more likely to fail to orient to all stimuli, with social stimuli being particularly challenging. They also took longer to orient to social stimuli and showed impairments in shared attention. Correlational analyses revealed that shared attention performance was related to the ability to orient to social stimuli, but not to nonsocial stimuli. These findings suggest that social orienting impairments may contribute to difficulties in shared attention in autism. The study used a naturalistic approach to examine social attention in young children with autism, which could be useful in clinical assessments. The participants included 20 children with autism or PDDNOS, 19 with Down syndrome, and 20 with typical development. Diagnoses were based on parent interviews and structured play sessions. Children with autism had higher nonverbal ability compared to those with Down syndrome and typically developing children. The study aimed to determine whether children with autism selectively failed to orient to social stimuli compared to nonsocial stimuli and whether impairments in social orienting were related to impairments in shared attention. The results support the hypothesis that difficulties in orienting to social stimuli may contribute to difficulties in shared attention in autism.