The paper identifies three major determinants of physical abuse: exposure to aggression, exposure to stressors, and access to resources. Data for this research were drawn from a case-comparison study that included 81 physically abusive and 148 nonabusive mothers. Logistic regression determined the relative importance of the predictors. The probability of child physical abuse varied in the expected direction with the number of emotional resources received (listening, help with decision-making, companionship), the number of stressors experienced, and the mothers' exposure to physical abuse by their own mothers, current and former partners. The estimation results showed that exposure to aggression in one's own childhood (abused by one's own mother) and exposure to domestic violence in one's adult life (abused by one's previous and current partners) were the most potent factors for predicting whether a mother would physically abuse her child. Figure, tables, references, appendix