The present study was based on follow-up data on 1409 persons interviewed 4 to 6 years after admission to drug treatment in the Drug Abuse Reporting Program (DARP). The admissions to DARP occurred in 1969-1971, and for most persons the follow-up data included 3 or more years after termination of DARP treatment. The study focused on variations in alcohol consumption associated with post-DARP drug use and treatment status. The results indicated that use of alcohol and non-opioid drugs (particularly marijuana) tended to be correlated, but that this was not true of opioid drugs. For a small segment of the sample, evidence suggested that substitution of use may have occurred between alcohol and opioid drugs. Also, persons with post-DARP drug treatment tended to use less alcohol than persons without treatment. Interpretations and implications of these findings are discussed.