The concept of selective survival to advanced ages is introduced and discussed in relation to the black/white mortality "crossover" in the United States. Crossover refers to the phenomenon wherein black mortality rates become lower than white mortality rates after approximately age 75. This reversal of mortality rates between advantaged and disadvantaged populations also occurs between Native Americans and whites. Such crossovers have significant implications for explaining differences in patterns of aging across populations. We argue that higher rates of selective survival in disadvantaged, high mortality populations result in a greater proportion of healthy, very old people who may require less nursing-home care, who have low suicide rates, and who enjoy higher status in the family and community. Differences between populations with regard to selective survival imply that chronological age alone is not always a useful measure of aging and old age. Finally, we identify further lines of inquiry about selective survival and its effects on aging.