Parental socio-cognitive factors may predict their physical discipline use as well as their perceptions of children's problem behavior; infant temperament may also influence parents' discipline use. Using a bidirectional approach, the current study investigated whether attitudes approving of parent-child aggression (PCA), negative child behavior attributions, knowledge of nonphysical discipline options, and infant temperament predicted 186 mothers' and 146 fathers' PCA use and child problem behaviors one year later. Findings indicated mothers who approved of PCA use and held negative child attributions were more likely to report greater subsequent PCA use; less knowledge of nonphysical discipline options predicted more perceived problem behaviors one year later. Fathers were more likely to engage in PCA with toddlers if they had less knowledge of nonphysical discipline options but also if they viewed their infants as active. Contributors to mothers' and fathers' PCA use and implications for prevention efforts and children's outcomes are considered.