Multivariate, biopsychosocial, explanatory models of mothers' and fathers' psychological and physical aggression toward their 3- to 7-year-old children were fitted and cross-validated in 453 representatively sampled families. Models explaining mothers' and fathers' aggression were substantially similar. Surprisingly, many variables identified as risk factors in the parental aggression and physical child abuse literatures, such as income, unrealistic expectations, and alcohol problems, although correlated with aggression bivariately, did not contribute uniquely to the models. In contrast, a small number of variables (i.e., child responsible attributions, overreactive discipline style, anger expression, and attitudes approving of aggression) appeared to be important pathways to parent aggression, mediating the effects of more distal risk factors. Models accounted for a moderate proportion of the variance in aggression.