Changes in children's attentional engagement were assessed as a function of their exposure to "teachers" who differed in perceived power and the communication style that is associated with perceived power. In Study 1, "teachers" (women assigned to an instructional role) were selected on the basis of their perceived power; low-power women were more likely than high-power women to display communication ambiguity. Children responded to low-power women with low levels of (1) autonomic orienting (consistent with low attention) and (2) high errors on a cognitively demanding task (mental arithmetic). Attentional disengagement was found to be mediated by the ambiguous communication style of low-power adults. In Study 2, the "teacher" was a confederate who systematically varied the facial and vocal ambiguity of her instructions. Children showed the lowest levels of orienting and the highest level of errors when the "teacher" was ambiguous in both face and voice. Results were interpreted as showing that adult ambiguity (naturally occurring or experimentally produced) leads to reductions in children's attentional engagement.