Interpersonal coordination forms an integral part of successful social interaction. Yet for psychopathologies that impact social functioning (e.g., autism, social anxiety), disruptions to coordination are widely documented. Little research however has considered the underlying mechanisms by which this association is sustained. To address this shortcoming, the current registered report investigated the extent to which key dynamical control parameters that govern interpersonal coordination (frequency matching and coupling) are impacted by traits associated with social anxiety and autism. In pairs, participants performed a pendulum swinging task known to reflect disruptions to the dynamics underlying coordination, while the level of task sociality was systematically varied (solo, observed, interactive). We quantified behaviour at both the individual (e.g., movement variability) and collective (e.g., coordination) levels via indices that are sensitive to changes in the parameters governing coordination. Consistent with past research, the results revealed negative associations between measures of coordination and symptoms of social anxiety and autism. Further, the findings highlighted disruption to the frequency matching parameter as a mechanism underlying the mental health-coordination link and identified coordination stability as a potential boundary condition of this relationship.