Can competition or cooperation for economic gain affect people’s social perceptions of others? This paper experimentally examines this possible link from the economic to the social realm. Subjects engage in a task facing either a tournament or a cooperative pay scheme, after which subjects are asked their social perceptions of their counterparts in the task — how similar they are and how much they have in common. The pay schemes do not affect answers to the subjective similarity measure but significantly influence subjects’ reports of commonality. Subjects who compete with counterparts for pay report fewer traits in common with their counterparts than do subjects facing the cooperative scheme. This treatment effect emerges even though our novel measure of commonality provides incentives to report accurately the number of common traits.