PROJECT SUMMARY/ABSTRACT Autism is a neurodevelopmental condition impacting 1 in 44 children that is diagnosed based on social communication challenges and restrictive/repetitive behaviors, including repetitive motor movements. While social communication differences in autistic individuals have been widely researched, motor skills, particularly those related to speech production, remain understudied. This gap in the literature is surprising given the growing evidence that motor differences are some of the earliest to emerge, are a clinically meaningful feature of autism that underlie many core symptoms, and are correlated with both receptive and expressive language skills. A few preliminary studies indicate that there are motor-based brain differences related to speech production and language in autism. These results suggest that the motor act of speech production may play a key role in the communication challenges observed in autism, however the brain and behavioral bases of speech motor profiles are currently poorly characterized. We can advance understanding of the underlying speech production motor differences, and related functional consequences, in autistic individuals through an improved characterization of the speech motor system and speech and language behaviors. Here, I propose to test the hypothesis that speech-motor brain regions are less engaged during speech production tasks in autistic compared to neurotypical (NT) adults, and that this disengagement is related to overall motor, speech, and language skills. I will recruit 30 NT adults and 45 autistic adults with diverse language profiles for an fMRI study paired with deep speech behavioral phenotyping. In Aim 1, I will use a novel functional localizer to identify and characterize the speech production network in each individual participant and compare the networks across groups. In Aim 2, I will use these individual networks as regions of interest in which to examine brain activation during a language- relevant speech production task, nonword repetition. As part of Aim 2, I will conduct deep speech and language phenotyping of the autistic adults, in order to obtain comprehensive profiles of their communication skills. I will then examine the relationship between the speech production activation during nonword repetition and each participant’s speech, language, and motor profiles. These aims will produce a novel localizer to characterize the speech production regions, elucidate speech-motor brain differences between NT and autistic adults, and provide key insights into the relationship between speech production related motor regions and communication in autism. Knowledge gained from this project will lead to a better understanding of role of the motor system in communication in autism across diverse language phenotypes.