Résumé : This study examines the influence of an audience's knowledge of the group membership of a target on the communication of information about this target. Participants were asked to rank order five traits to describe a person labelled as an engineer to an imaginary audience. Overall they were more likely to choose traits stereotypical of the target's social category when the audience was presented as unaware than aware of this category membership. Within-participants analyses also indicated that the perceived stereotypicality of a trait predicted its communication more positively when the audience was unaware than aware of the target's social category. These results can be interpreted in line with the maxim of quantity (Grice, 1975): stereotype-consistent information being more informative when the audience is unaware than aware of the target's social category, it is more likely to be communicated in the former than in the latter case.