This prospective study sought to identify sociodemographic and psychosocial risk factors for unintentional infant injuries that occurred in or around the home. It also examined whether social support modified the relationship between high maternal stress and infant injury. The subjects were 367 mothers who were interviewed six to eight weeks after their newborn infants were discharged from the hospital, and approximately one year later, when 132 infants (36%) were reported as injured (burned, poisoned, serious fall, airway problem). Logistic regression analyses established that family conflict was the most significant predictor of unintentional infant injury, followed by fewer than two siblings living in the home at the first interview, and maternal unemployment. In addition, among mothers with high stress, the use of social support resulted in fewer unintentional infant injuries.