The surge of national assertion in the USSR, generally unanticipated by American decision-makers, focusses attention on ethnic issues worldwide. But the moral dimension of ethnicity has rarely been examined in a comparative context, especially from the religious point of view. Issues now critical in the Soviet Union, such as justification for educational and occupational quotas for disadvantaged minorities, and the right of vulnerable ethnic collectivities to preserve their cultures by limiting immigration, have major implications for Third World and European countries, which are briefly surveyed. In the United States, concern for producing a united national culture based on the ideal of equal opportunities for individuals has usually precluded attention to preservation of ethnic collectivities distinct from the majority culture. Since most of these collectivities have been traditionally Catholic, their preservation has been especially sensitive to changes in American Catholicism.