In recent years, there has been a renewal of interest in the processes through which groups coordinate social perceptions and judgement. This topic is particularly important for the study of stereotyping, as most of the impact of stereotypes derives from the fact that they are widely shared within social groups. The present experiment (N = 132) tests the assertion that perceivers are more likely to generate a shared in-group stereotype to the extent that they define themselves and interact in terms of a common social category membership. Results supported predictions, indicating that manipulations intended to heighten social identity salience affected the content of self-categorizations leading to enhanced stereotype consensus and favorableness. As predicted, effects apparent when individuals completed stereotype checklists were also enhanced when checklists were completed in groups. These results are consistent with predictions derived from self-categorization theory and point to the capacity for internalized group memberships to structure and regulate cognition.