We explore the effect of identity salience on behaviour in a simple social interaction. Specifically, we compare ultimatum bargaining across three treatments: priming subjects with a shared identity, priming subjects with an identity distinct from those with whom they will interact, and priming subjects with no particular identity. We find that subjects are most cooperative in the identity-priming treatment and least cooperative in the distinctiveness-priming treatment. Similarly, subjects reveal the highest demands in the identity-priming treatment and the lowest demands in the distinctiveness-priming treatment. We discuss the implications of these results with respect to the literature on organizational identity.