The celebration of communitarianism by political philosophers (Sandel 1982) has apparently been extended to strategic analyses of ascriptively attuned norms (Fearon and Laitin 1996)—an intriguing development, given game theory's individualistic premises. We believe, however, that game theory offers little comfort to prescriptive theories of communitarian rules: a hardheaded strategic analysis supports the Enlightenment view that such norms tend to be Pareto inefficient or distributionally unjust. This paper uses a specific criterion — supporting cooperation as a Nash equilibrium — to compare communitarian norms, which turn on people's ascriptive identities, to universalistic ones, which focus on people's actions. We show that universalistic rules are better at stabilizing cooperation in a broad class of circumstances. Moreover, communitarian norms hurt minorities the most, and the advantages of universalism become more pronounced the more ascriptively fragmented a society is or the smaller is the minority group.