Little is known about the role children's processing of emotions plays in altering children's vulnerability to interparental conflict. To address this gap, the present study examined whether the mediational cascade involving children's exposure to interparental conflict, their insecure responses to interparental conflict, and their psychological problems varied as a function of children's preexisting biases to attend to angry, fearful, sad, and happy expressions. Participants included 243 children (M age = 4.60 years) and their parents assessed at 3 annual measurement occasions. Moderated-mediation analyses within a cross-lagged autoregressive design indicated that the indirect paths among interparental conflict, emotional insecurity, and psychological problems were significant for children who exhibited greater attentional biases toward angry and fearful emotions. Greater attention to anger and fear specifically moderated the first link in the mediational path. Interparental conflict was a significantly stronger predictor of emotional insecurity for children who attended to angry and fearful cues longer. Consistent with environmental sensitivity theories, children with attentional biases to angry and fearful emotions exhibited disproportionately higher levels of emotional insecurity following exposure to heightened interparental conflict but also lower levels of emotional insecurity after experiencing minimal interparental conflict.