Although dialectical behavior therapy (DBT) has been efficacious in controlled studies, its effectiveness in community settings, and for patients with borderline personality disorder (BPD) and comorbid depression, remain to be determined. My research will address these questions within the framework of effectiveness research, by comparing DBT with treatment as usual. Factors that contribute to patient attrition and outcome from DBT will also be identified, including universal change processes and patient characteristics. Individuals with comorbid BPD and major depressive disorder will be randomly assigned to either DBT or a treatment as usual condition. Assessments will be obtained prior to, during, and at posttreatment (12 months). DBT treatment adherence will be assessed and treatment groups will be compared on a number of outcome variables including severity of depression and number and severity of parasuicidal acts.