Conventional wisdom suggests that cultural differences make conflict more likely. Culture can unite and divide, but there exists little agreement among scholars over how identity forms among states, what distinctions are most salient, and when conflict is more likely. Researchers have tended to ‘confirm’ the role of identity in an ex post facto fashion, looking only at actual conflicts with cultural differences, without considering the opportunities for conflict among groups. We address a series of problems with existing conceptions of identity and ethnicity. We distinguish between shared and different culture by religion, language, and ethnicity. Rather than equating states with just the dominant groups, we also consider how relations involving secondary groups present in other states can give rise to conflict. We examine empirically the relationship between cultural similarities and differences and international dispute behavior in the post-World War II era. Our results suggest that culture and identity influence dispute patterns, but in ways that run counter to conventional beliefs. We find little evidence that conflict is more common between states where the dominant groups come from different cultural affiliations. If anything, our results suggest that violence is more likely among states with similar cultural ties, even when controlling for other determinants of conflict. Moreover, dyads where a group is politically privileged in one state but a minority in another tend to be particularly conflict prone. We conclude with suggestions for reorienting the study of identity and conflict in more constructive ways than the clash of civilization thesis.