The primary functional role of conversational hand gestures in narrative discourse is disputed. A novel experimental technique investigated whether gestures function primarily to aid speech production by the speaker, or communication to the listener. The experiment involved repeated narration of a cartoon story or stories to a single or multiple listeners. The pattern of results matched that predicted by the communication hypothesis. In a second experiment, the effects of attention in the listener were investigated. Significant differences were found in gesture production when narrating to attentive versus inattentive listeners. These results support the theory that during a narrative task gestures are produced primarily for the benefit of the listener. Our technique can readily be generalized to other tasks and contexts.