Ethnic diversity within metropolitan neighborhoods increased during the 1970s, and all-white tracts became less common. The simple presence of a minority group did not precipitate turnover, but as the minority proportion rose, the probability of racial and ethnic transition increased. Tracts with multiple groups became much more common during the decade and were especially prone to transition. Distinctively, black neighborhoods displayed a bipolar clustering at both ends of the distribution of minority presence. Multivariate models showed that white loss was increased by the presence of multiple minority groups, by a higher minority proportion, and by location near existing minority areas.