Although a cycle of harsh and abusive parenting has been recognized for decades, this cycle is not inevitable. Indeed, the mechanisms underlying such patterns, and the resources parents may access to disrupt this cycle, require further study. Research investigating those processes has either relied on cross-sectional designs or largely assessed mediators or moderators at one time point. The current investigation of parent–child aggression (PCA) risk utilized a longitudinal design to consider possible mediators and moderators across three time points. Mothers and fathers reported on their personal history of physical and psychological abuse during the last trimester of the mother’s pregnancy; their PCA risk was assessed concurrently when their child was 6 months and when their child was 18 months. Current findings support several mediators for mothers, although fewer for fathers, prenatally, but mediation was not observed across time. Similarly, several moderators of the effect of personal history of physical and psychological aggression on PCA risk were identified prenatally but not across time. Thus, several qualities believed to account for, or mitigate, the intergenerational transmission of PCA may not be consistent—underscoring the continued need to identify factors that account for the cyclical process versus what may interrupt intergenerational transmission.