Data on lifetime alcohol and heroin use by 443 White and Chicano addicts of both genders were obtained from a sample of admissions to several Southern California methadone maintenance programs. Patterns of alcohol and heroin use were examined with respect to gender and ethnic differences. Repeated-measures MANOVA established an inverse pattern of alcohol and heroin use for all four groups, confirming and extending the findings of a previous study by the authors. With this additional evidence, the authors propose a compensatory model that explains the obtained inverse pattern of alcohol and heroin use and that may be suitable in examining concurrent or sequential use of other psychoactive substances in addition to alcohol. Significantly higher levels of heavy alcohol use were reported by Chicano than by White addicts. Overall findings indicate that after heroin addiction occurs, there is a convergence in patterns of substance use by both genders, although variations related to ethnicity persist, particularly for alcohol use.