Interpersonal motor coordination is considered to be an integral part of maintaining successful social interactions. Research has shown that simply coordinating one’s movements with another actor can influence rapport as well as feelings of social connection and social competence. Past research has also found that deficits in social motor coordination are associated with psychological dysfunction such as schizophrenia and borderline personality disorders. However, the potential association between interpersonal motor coordination and autism spectrum disorder (ASD) has only received a very limited amount of attention. In the current experiment, children who had been previously diagnosed with ASD and typically developing (TD) children were asked to synchronize with or imitate the movements of an experimenter in two different interpersonal motor tasks: object tapping and hand-clapping. Both the experimenter’s and the participants’ movements were captured and compared to each other using relative phase analysis and cross-recurrence quantification analysis (CRQA). The results reveal differences not only in the patterning of the coordination that occurred for ASD and TD children, but also in the stability and deterministic structure of the coordination. Of particular interest was the finding that children with ASD exhibited less stable (robust), but more deterministic patterns of interpersonal social motor coordination compared to TD children.