The basic purpose of this collaborative research is to assess the efficacy, efficiency, and safety of two well-defined, short-term psychological therapies, Cognitive Behavioral Therapy and Interpersonal Psychotherapy, for treating unipolar, nonpsychotic outpatient depression. The psychotherapies will be compared to a treatment demonstrated to be effective for this patient population, a tricyclic antidepressant medication (imipramine). A pill-placebo condition is also included to establish the adequacy of the antidepressant drug as a reference treatment. Outcome will be evaluated in terms of symptomatology, general clinical status, and social functioning and will be measured at monthly intervals during the 16-week treatments, at termination, and at three follow-up points (6, 12, and 18 months after termination). The study will be conducted simultaneously at three research sites, using a final common research protocol. The research has two phases, a pilot-training period and a treatment outcome study. The objectives of the first phase, now nearing completion, include the training of independent clinical evaluators and training of therapists in the different modalities, the testing of patient selection criteria, evaluation of patient flow and assessment instruments, the use of the treatments by the therapists and a test run of the experimental design itself. The current application describes results of the pilot work and details of the specific procedures for the treatment outcome study (which will involve the treatment, periodic assessment and long-term follow-up of 80 depressed outpatients), methods of data analysis and plans for reporting findings.