This research examined the role of mothers' cognitions about children's self-control in their responses to children's helplessness. Mothers and their four-year-old children (N = 109) were asked to work on a difficult task in the laboratory. Mothers' hostility and warmth as well as children's helpless (vs. mastery) behavior were coded every minute. Mothers also completed a set of questionnaires assessing their cognitions about children's self-control. Hierarchical linear modeling indicated variability among mothers in their minute-to-minute hostility, but not warmth, in response to children's helplessness. Mothers' cognitions contributed to this variability: The more mothers placed importance on, worried about, and believed they could influence their children's self-control, the more hostility they demonstrated following their children's helplessness.