Longitudinal patterns of alcohol use by narcotics addicts sampled from a drug-free treatment program and from several methadone maintenance treatment programs were examined. Overall, a high prevalence of alcohol use was found in both samples across several stages of the addicts' careers. Many addicts were also using nonnarcotic drugs and marijuana concurrently. Generally, levels of alcohol, as well as of other substances use, decreased as the narcotics addiction career began. Unlike other drug use, however, only alcohol consumption increased whenever a decrease occurred in narcotics use. Effects of ethnicity, gender, parental alcohol problems, and opiate and alcohol use onset sequence on the alcohol- and narcotics-related behavior are examined in detail. A pattern of early onset of heavy alcohol consumption before initial narcotics addiction was more common among Chicanos and was associated with a positive parental alcohol history. Women addicts typically had a much lower alcohol consumption level than their male counterparts. Among the 160 deaths of the original 581 addicts followed during the 20 years of the study, alcohol-related deaths accounted for 17.5% of the total. Treatment implications for addicts with an alcohol problem are discussed.