Rhythm and timing are critical to successful social interactions as rhythm sensitivity enables us to form predictions and adapt and coordinate our behavior with each other. This is particularly evident during spoken communication such as through the occurrence of conversational entrainment (or convergence), in which interlocutors temporally adapt their speech patterns to those of their partner. We recently demonstrated links between rhythm and speech entrainment by adapting a novel and automated beat-tracking algorithm, originally designed for use with musical rhythms, to speech in order to reveal the underlying metrical timing of spoken utterances. We observed that typically developing adults converge their speech rhythms during spontaneous conversation, suggesting an underlying rhythm mechanism that is present in spoken communication. This conversational entrainment process occurs automatically but is also moderated by social factors: Greater conversational entrainment occurs between dyads with higher versus lower social agreement throughout the interaction. These results, which suggest that both underlying rhythm processing and situational social factors contribute to interpersonal communication, inform mechanisms of social communication in typical development, as well as disruptions in social communication in autism (ASD). A common and lifelong disorder, individuals on the autism spectrum exhibit challenges in rhythm and timing of social communication and interaction including reduced interpersonal coordination. Individuals on the autism spectrum also exhibit impairments in non-social rhythm skills, with particular difficulties perceiving and synchronizing motor movements to a regular auditory beat. Building on our prior work, the current project proposes that impairments in flexibly tracking and updating rhythmic behavior underlies challenges across sensorimotor and social communication domains in autism. This R21 study investigates underlying processes and outcomes of conversational entrainment in adults with and without autism including the relationship between sensorimotor synchronization and conversational entrainment (Aim 1), adaptation to dynamic social factors as a moderator of conversational entrainment (Aim 2), and conversational entrainment as a predictor of social affiliation (Aim 3). In accordance with PA-21-200, this project advances research into the role of sensory, motor, and social factors in social interactions and communication in autism. Results will inform theories of communication impairment focused on specific rhythmic processes as an underlying mechanism disrupted in autism and demonstrate how individual and dyadic attributes contribute to social communication success.