The rates of alcohol use among immigrants were lower than among native-born adults. Rates of tobacco use among immigrants were also lower than among native-born adults. This pattern continued for rates of illicit drug use. An analysis that adjusted for demographic differences showed that immigrants who had been in the United States for 5 or more years were more likely than immigrants who had been in the country for fewer than 5 years to use alcohol in the past year or past month, to binge drink, to use marijuana in the past year or month, and to use any illicit drug in the past year or month. Immigrants' tobacco use was not significantly associated with length of time in the United States. Estimates of substance use among immigrants from 16 selected countries showed wide variation, even within geographic regions. Past month alcohol use rates among immigrants from the United Kingdom (67.5 percent) and Canada (64.5 percent) were significantly higher than the rate among native-born adults (52.4 percent). Immigrants born in the Philippines, Vietnam, India, and China had rates significantly below rates among immigrants from other selected Asian countries and among native-born adults. None of the 16 countries had adult immigrant populations with past-month tobacco use rates higher than the native-born rate. Immigrants from several countries had rates of past-month illicit drug use that were similar to the native-born rate of 6.6 percent. These included Japan, Puerto Rico, Korea, Jamaica, Poland, Germany, and the United Kingdom. Extensive tables and figures, 35 references, and appended supplementary information