We experimentally investigate the relationship between discriminatory behaviour and the perceived social inappropriateness of discrimination. We conjecture that discrimination will be weaker when social norms oppose it. Our results support this prediction. Using a Krupka-Weber social norm elicitation task, we find participants perceive it to be more socially inappropriate to discriminate on the basis of nationality than on the basis of social identities artificially induced using a trivial minimal group technique. Correspondingly, we find that participants discriminate more in the artificial identity setting. Our results suggest norms and the preference to comply with them affect discriminatory decisions and that the social inappropriateness of discrimination moderates discriminatory behaviour.