Previous research on biomarkers of individual differences in sensitivity to caregiving contexts has largely focused on children’s parasympathetic activity, commonly indexed by RSA. Recent work, however, suggests that the parent–child dyadic RSA concordance may also provide important insight into heterogeneity in the links between parenting behaviors and children’s adjustment outcomes. This study is among the first to characterize dyadic patterns of RSA concordance between behaviorally inhibited children aged 3.5 to 5 years old (54% female, 47% White) and their caregivers (n = 107 dyads) across tasks designed to mimic children’s exposure to novel social interactions while parents observed their children navigating these tasks. Furthermore, we examined dyadic RSA concordance as a potential moderator of the associations between nurturing and intrusive parenting behaviors and children’s adjustment problems, as reported by teachers and parents. We found that a more positive concordance (i.e., caregivers and children demonstrated similar patterns of epoch-to-epoch RSA change across tasks) protected against teacher-reported internalizing problems in the context of low parental nurturance. A negative concordance (i.e., caregivers and children demonstrated dissimilar patterns of epoch-to-epoch RSA change across tasks), however, exacerbated the risk for parents’ reports of children’s externalizing behaviors in the context of high parental intrusion.