Objective: Behavioral couples therapy (BCT) is more efficacious than individually-based therapy (IBT) for substance and relationship outcomes among substance use disorder patients. This study compared BCT with IBT for drug-abusing women. Method: Sixty-one women, mostly White, late 30s, with primary substance use disorder other than alcohol (74% opioid), and male partners were randomized to 26 sessions over 13 weeks of BCT plus 12-step-oriented IBT (i.e., BCT + IBT) or IBT. Substance-related outcomes were percentage days abstinent (PDA), percentage days drug use (PDDU), Inventory of Drug Use Consequences. Relationship outcomes were Dyadic Adjustment Scale (DAS), days separated. Data were collected at baseline, posttreatment, and quarterly for 1-year follow-up. Results: On PDA, PDDU, and substance-related problems, both BCT + IBT and IBT patients showed significant (p < .01) large effect size improvements throughout 1-year follow-up (d > .8 for most time periods). BCT + IBT showed a significant (p < .001) large effect size (d = −.85) advantage versus IBT on fewer substance-related problems, while BCT + IBT and IBT did not differ on PDA or PDDU (ps > .47). On relationship outcomes, compared to IBT, BCT + IBT had significantly higher male-reported Dyadic Adjustment Scale (p < .001, d = .57) and fewer days separated (p = .01, d = −.47) throughout 1-year follow-up. Conclusion: BCT + IBT for drug-abusing women was more efficacious than IBT in improving relationship satisfaction and preventing relationship breakup. On substance use and substance-related problems, women receiving both treatments substantially improved, and women receiving BCT + IBT had fewer substance-related problems than IBT.