The comorbidity, separately, of alcohol dependence and consequences of drinking with illicit drug use is compared between Mexicans and Mexicans Americans, using data from the 1995 and 2000 U.S. National Alcohol Surveys (n = 830) and the 1998 Mexico National Household Survey on Addictions (n = 3313). Among drinkers, comorbidity was significantly more prevalent among Mexican Americans than among Mexicans and was positively associated with level of acculturation among Mexican Americans. Although data may not be generalizable, they are important for a better understanding of cultural influences on the development of comorbid substance abuse* conditions among Mexicans immigrating to the United States and their substance abuse treatment needs.