This research concerns the location and stability of highly racially diverse census tracts in the United States. Like some other scholars, the authors define such tracts conservatively, requiring the significant presence of at least three racialized groups. Of the approximately 65,000 tracts in the country, there were 197 highly diverse tracts in 1990 and 998 in 2010. Most were located in large metropolitan areas. Stably integrated highly diverse tracts were the exception rather than the rule. The vast majority of highly diverse tracts transitioned to that state from being predominantly White. Those that transitioned from being highly racially diverse were most likely to transition to being majority Latino. Although the absolute level of metropolitan racial diversity has no effect on the stability of high-diversity tracts, change in both metropolitan-scale racial diversity and population raise the probability of a tract’s transitioning to high diversity. Metropolitan-scale racial diversity did not affect the stability of highly diverse tracts, but it did alter the patterns of succession from them. The authors also found that highly diverse tracts were unstable and less likely to form in metropolitan areas with high percentages of Blacks. Increased metropolitan-level diversity mutes this Black population share effect by reducing the probability of high-diversity tract succession to a Black majority.