Specialized substance abuse treatment for parenting women is thought to improve outcomes, but long-term impacts and how they occur are poorly understood. Utilizing a sample of 789 California mothers followed for 10 years after admission to women-only (WO) or mixed-gender (MG) drug treatment, we examine the relationship between WO treatment and outcomes and whether it is mediated by post-treatment exposures to criminal justice and health services systems. At follow-up, 48% of mothers had a successful outcome (i.e., no use of illicit drugs, not involved with the criminal justice system, alive). Controlling for patient characteristics, WO (vs. MG) treatment increased the odds of successful outcome by 44%. In the structural equation model WO treatment was associated with fewer post-treatment arrests, which was associated with better outcomes. Women-only substance abuse treatment has long-term benefits for drug-dependent mothers, a relationship that may be partially explained by post-treatment exposure to the criminal justice system. Findings underscore additional leverage points for relapse prevention and recovery-supportive efforts for drug-dependent mothers. Published by Elsevier Inc.