Project Summary Autism spectrum disorder (ASD) is associated with marked heterogeneity with respect to the development of executive function (EF) abilities. In the United States, 12 million children primarily speak a language other than English in the home, suggesting that 1 in 4 children with ASD are being raised in a bilingual environment. Individuals who speak two languages fluently sometimes perform better on tasks of EF than monolingual individuals. Despite the potential advantages that bilingualism may confer, clinical practitioners commonly advise against providing a bilingual environment for children with developmental disabilities. The rationale for this recommendation is that concentrating on one language should better support a child’s language development. Yet, a growing body of work suggests there are no negative effects of being raised in a bilingual environment for children with neurodevelopmental disorders. Preliminary evidence even suggests possible associations between bilingualism and enhanced EF in some children with ASD. Still, there is little research specific to bilingualism in children with ASD, leaving clinicians struggling to develop informed recommendations for families of children with the disorder. Currently, there is no research characterizing the relationship between bilingualism, EF abilities, and brain network organization in children with ASD. This project will investigate these links for the first time. This exploratory project will examine the neural basis of EF in 50 monolingual and 50 bilingual children with ASD between the ages of 8-12 years with two aims: 1) to characterize associations between bilingualism and EF abilities in children with ASD using an informant-report indicator of EF and performance-based laboratory tasks, and 2) to characterize associations between bilingualism and brain functional organization underlying EF abilities in children with ASD using both task- based fMRI and resting-state functional connectivity dynamics. The project will be conducted in Los Angeles, where nearly 60% of the population is bilingual. This research addresses the strategic plan from the Interagency Autism Coordinating Committee that aspires to understand alterations in brain function in ASD to better enable the development of targeted interventions and societal accommodations that improve quality of life for individuals on the spectrum.