This 9-month naturalistic study investigated maternal influence on the responses of 1 1/2- to 2-year-old infants to emotional distress events occurring in the family environment. Mothers were trained to report details of distress incidents, of the child's reactions to the person in distress, and of the mother's own response to the child and to the victim. The mothers of 16 infants were instructed to tape record (in narrative style) an account of events in which their child was the cause of someone's physical or psychological distress, and those in which the child was a bystander. Every third week an investigator visited the home to supervise the mother's data collection, to simulate an emotion and to assess mother-child interactions. Analysis of maternal techniques indicated that mothers were not very active when their children were bystanders to distress. The little teaching they did do seemed not to influence children's altruism. However, mothers' disciplinary techniques regarding distress caused by their children emerged as a salient element in the child's moral learning: (1) mothers' high use of affective explanations when the child transgressed was significantly linked with more reparation from their children, while neutrally delivered explanations were unrelated to children's reparation; (2) the more altruistic children in innocent bystander situations were those whose mothers used affective explanations in handling their child in transgression situations; and (3) the frequent use of unexplained prohibitions as a disciplinary technique tended to deter learning of altruistic responses. (Author/SS)