Beginning with the hypothesis that cohesiveness in group therapy is the analogue of relationship in individual therapy, this chapter deals with the available evidence for group cohesiveness as a therapeutic factor and the various pathways through which it exerts a therapeutic influence.
Over the past thirty years, a vast number of controlled studies of psychotherapy outcome have been performed. Competent, comprehensive reviews of the entire research evidence persuasively demonstrate that, overall, psychotherapy is an effective endeavor: approximately two-thirds of patients who receive psychotherapy are "moderately" to "much" improved. 1 One particularly rigorous review of 475 controlled studies concluded that the average person who receives psychotherapy is better off at the end of it than 80 percent of people who do not, and that the outcome from group therapy is virtually identical to that of individual therapy. 2 Other reviews of rigorous research support the effectiveness of group therapy, both in an absolute sense and in comparison to other psychotherapies. 3
The research evidence for the overall effectiveness of group psychotherapy is so compelling that it is time to direct our efforts toward a fuller understanding of the necessary conditions for effective psychotherapy. After all, not all psychotherapy is successful. In fact, there is evidence that treatment may be for better or for worse--though most therapists help their patients, some therapists make some patients worse. 4 Why? What makes for successful therapy? Although many factors are involved, a sine qua non for effective therapy outcome is a proper therapeutic relationship. 5 The best research evidence available overwhelmingly supports the conclusion that successful therapy is medi