The proposed research is designed to continue the clinical evaluation of the efficacy of Dialectical Behavior Therapy (DBT) with chronically parasuicidal women with borderline personality disorder (BPD). Previous research has demonstrated the efficacy of standard DBT, which consists of concurrent individual psychotherapy and group behavioral skills training, with this patient population. What remains unclear is whether these results can be replicated under more tightly controlled conditions (e.g., guaranteeing that all subjects in the control group minimally receive psychotherapy). The proposed treatment study addresses this question and aims to accomplish the following: l) to complete our current randomized clinical trial evaluating the efficacy of one year of DBT as compared to one year of Treatment-by-Experts provided in the community (TBE); and 2) to analyze whether treatment characteristics that are theoretically linked to DBT and that are defined as DBT strategies are, in fact, predictive of treatment response. Potential confounds from previous studies of the efficacy of DBT are tightly controlled within this trial. In continuation of the current study, we will add 57 more subjects total, 28 in DBT and 29 in TBE, to bring the study to the originally-intended 60 subjects per cell. Outcome measures for this study will assess suicidal behaviors, therapy-interfering behaviors (e.g., treatment compliance), and quality of life interfering behaviors (e.g., psychiatric hospitalization, affect, social functioning, and global functioning). Subjects will be assessed at pretreatment, at 4-month intervals during the treatment year, and at 4-month intervals for one year following treatment. Additional daily patient ratings and weekly patient and therapist ratings for subjects in the DBT condition will be obtained.