Links between social support and relapse were examined in a study of alcoholics, cigarette smokers, and opiate users completing treatment for drug use (N = 221). Subjects were followed weekly until relapse for a maximum of 12 weeks after the end of treatment. Structural and functional social support and support for abstinence and drug use were investigated. With demographic variables and drug-treatment group controlled, greater structural support (as measured by an index of social integration and by partner status) predicted a lower risk of relapse. Greater experienced partner support for abstinence also predicted lower risk. Social network members' use of the subject's problem drug predicted heightened relapse risk, but the effect was not statistically significant. This study contributes to a cross-drug model of relapse. It highlights the importance of social integration and abstinence-specific functional support in predicting the risk of relapse, independent of the particular drug of abuse.