Adults often attribute internal dispositions to other people and down-play situational factors as explanations of behavior. A few studies have addressed the origins of this proclivity, but none has examined emotions, which rank among the more important dispositions that we attribute to others. Two experiments (N = 270) explored 15-month-old infants' predictive generalizations about other people's emotions. In exposure trials, infants watched an adult (Experimenter) perform actions on a series of objects and observed another adult (Emoter) react with either anger or neutral affect. Infants were then handed the objects to test whether they would imitate the Experimenter's actions. One chief novelty of the study was the inclusion of a generalization trial, in which the Experimenter performed a novel act on a novel object. We systematically manipulated whether the Emoter did or did not respond angrily to this novel demonstration, and whether the Emoter watched the infant's response. Even when no further emotional information was presented in the generalization trial, infants were still hesitant to perform the act when the previously angry Emoter was watching them. Infants tracked the Emoter's affective behavior and, based on her emotional history, they predicted that she would become angry again if she saw them perform a novel act. Making predictive generalizations of this type may be a precursor to more mature trait-like attributions about another person's emotional dispositions.