There are many ethical, logistical, and methodological problems in designing and conducting rigorous treatment outcome studies for dissociative identity disorder. Treatment to stable integration often takes 4 or 5 years. It would be unethical to randomly assign subjects to a placebo group for that long. Therapists who believe in the specificity of psychotherapy for dissociative identity disorder would be unlikely, as a matter of personal conscience, to participate in a study that involved random assignment to 5 years of placebo treatment. Therefore, one could not recruit therapists to the study. The likelihood that patients would stay in the study in the placebo control condition for that long without dropping out is minimal.