The present study examined the impact of domestic violence (DV) on children's emotion regulation abilities measured via baseline vagal tone (VT). Specifically, the authors examined the relationship between DV exposure and children's regulatory functioning over time, investigating whether DV exposure was related to the trajectory of children's physiological regulatory abilities from the preschool period to middle childhood. Covariates, including marital dissatisfaction and conduct-problem status, along with potential gender differences, were examined. Though all children increased in baseline VT from Time 1 to Time 2, children exposed to DV displayed less increase in baseline VT over time as compared to nonexposed children. Results in terms of the long-term outcomes of DV on children and implications for interventions were taken into consideration and discussed in the article. (Contains 2 tables.)