This study examined interparental conflict as a curvilinear predictor of children's reactivity to interparental conflict and, in turn, their school problems across three annual measurements. Participants included 243 preschool children (M[subscript age] = 4.60 years; 56% girls) and their parents from racially (e.g., 48% Black; 16% Latinx) diverse backgrounds. Interparental conflict was a significant quadratic predictor of children's emotional reactivity ([beta] = 0.23) and behavioral dysregulation ([beta] = 0.27) to conflict over a 1-year period. The robust association between interparental conflict and behavioral dysregulation weakened at high levels of interparental conflict. In contrast, interparental conflict more strongly predicted children's emotional reactivity as conflict exposure increased. Children's emotional reactivity, in turn, predicted their greater school problems 1 year later ([beta] = 0.25).