The primary aim of this proposal is to evaluate the effectiveness of Dialectical Behavior Therapy for Substance Abusers (DBT-S), an outpatient treatment for women who meet criteria for both substance abuse and borderline personality disorder (BPD). DBT-S is based on an existing cognitive-behavioral treatment (Dialectical Behavior Therapy; DBT) which has been shown in other research to be effective for severely dysfunctional women who meet criteria for BPD. Females meeting criteria for BPD and for current substance dependence will be randomly assigned to one of two one-year treatment conditions: (1) DBT-S (n=50), or (2) Twelve-Step Counseling (TSC) (n=50). The TSC is based on the 12-Step philosophy and aims to facilitate the client's involvement in the 12-Step fellowship. DBT-S subjects will receive weekly individual therapy, skills training group, and individual skills training. TSC subjects will receive weekly individual therapy, weekly group based on-the """"""""12&12"""""""" 12-Step meeting format, weekly participation in 12-Step meetings, and sponsor meetings. All subjects who are opiate-dependent will be maintained on LAAM an opiate replacement. Subjects in both conditions will receive case management, psychotropic drug monitoring and tapering. Outcomes targeted and measured include reductions in substance abuse, suicidal behaviors, therapy-interfering behaviors, general psychopathology, enhancement of general functioning, and interpersonal skills. The major assessment battery will be administered at pre-, 4-month, 8-month, and 12-month intervals during and immediately post-treatment, with follow-ups conducted at 4-month intervals for one year thereafter. Additional client and therapist ratings and three times weekly drug testing will be conducted. Observation of treatment sessions, weekly case consultation meeting for each treatment team, and on-going adherence coding will be used to monitor treatment delivery.