The health status of immigrants is of vital interest to health policy planners as the number of immigrants in the United States increases. This report has shown that, overall, foreign-born persons had better health than the U.S.-born population, although this health advantage varied by length of residence in the United States. In virtually every measure of health status, and with regard to almost every sociodemographic characteristic, the most recent immigrants were healthier than foreign-born persons who have lived in the United States 10 years or more as well as healthier than the U.S.-born population. Immigrants who had lived in the United States 10 years or longer were generally healthier than U.S.-born adults, although the differences were not as striking as between recent immigrants and the native-born population. These findings may be explained in several ways. First, recent cohorts of immigrants may have been healthier than earlier cohorts of immigrants at the time of immigration. If so, as their duration of residence in the United States increases, they will continue to be significantly healthier than native-born persons. Second, earlier cohorts of immigrants may have been as healthy as recent cohorts at the time of immigration, but their health has deteriorated with increased duration of residence in the United States. This suggests that immigrants had or acquired physical conditions or behaviors that put them at risk in their new environment or that access to health care has been limited. It also suggests that more recent cohorts of immigrants could experience a similar deterioration of health as their duration of residence in the United States increases. Finally, these findings may reflect a combination of these influences or other factors not considered. To understand these patterns will require additional research, including comparative studies of the health of immigrants in the United States with the health of nonmigrants (stayers) in the countries of immigrant origin.