We interpret the social identity literature and examine its economic implications. We model a population of agents from two exogenous and well defined social groups. Agents are randomly matched to play a reduced form bargaining game. We show that this struggle for resources drives a conflict through the rational destruction of surplus. We assume that the population contains both unbiased and biased players. Biased players aggressively discriminate against members of the other social group. The existence and specification of the biased player is motivated by the social identity literature. For unbiased players, group membership has no payoff relevant consequences. We show that the unbiased players can contribute to the conflict by aggressively discriminating and that this behavior is consistent with existing empirical evidence.