A person’s speech communicates his or her thoughts and feelings. We predicted that beyond conveying the contents of a person’s mind, a person’s speech also conveys mental capacity, such that hearing a person explain his or her beliefs makes the person seem more mentally capable—and therefore seem to possess more uniquely human mental traits—than reading the same content. We expected this effect to emerge when people are perceived as relatively mindless, such as when they disagree with the evaluator’s own beliefs. Three experiments involving polarizing attitudinal issues and political opinions supported these hypotheses. A fourth experiment identified paralinguistic cues in the human voice that convey basic mental capacities. These results suggest that the medium through which people communicate may systematically influence the impressions they form of each other. The tendency to denigrate the minds of the opposition may be tempered by giving them, quite literally, a voice.