Adolescents with Autism Spectrum Disorder (ASD) exhibit impairments in social interactions that last throughout their lives and at the core of thes impairments are social communication deficits. These deficits include an inability to display or reciprocate appropriate verbal and nonverbal aspects of communication and, in turn, successfully carry out and maintain effective social interactions. These deficits can severely impede learning and overall social functioning at home and in school, as well as make successful treatment difficult. Historically, the research and assessment tools used to identify and understand the communication deficits present in the ASD population have centered on qualitative measures of the semantic, pragmatic and nonverbal qualities of communication. However, recent advances in the quantitative and computational measurement of conversational content has resulted in a novel set of methods that might provide a more objective and reliable way of identifying the conversational (behavioral) markers of ASD, as well as a better understanding of the time- evolving dynamics of social communication in individuals with ASD. These new computational methods also promote a multivariate assessment of communicative social interactions by relating the verbal aspects of social communication with the complex and highly interrelated aspects of non-verbal behavior, which includes an often overlooked aspect of social communication, namely, the spontaneous social motor coordination that emerges during social interactions. A growing body of social psychological research has found that these subtle and sometimes non-obvious aspects of social interaction are fundamental for maintaining a communicative exchange and promoting interpersonal responsiveness and verbal comprehension. Recent research has also demonstrated how social motor coordination can promote social rapport and positive self-other relations. Moreover, significant differences between typically developing children and children with ASD in the occurrence and patterning of social motor coordination have been found and are highly correlated with social cognitive functioning. Accordingly, the objective of the current proposal i to (i) validate the use of newly developed computational measures of conversational interaction for assessing deficits in social communication in adolescents with ASD and (ii) further identify whether deficits in social communication are interrelated to deficits in the social motor coordination that supports effective social interaction.