Where are the commonalities among the therapeutic common factors?

There is little convergence or empirical research on factors shared by diverse psychotherapies. We reviewed 50 publications to discern commonalities among proposed therapeutic common factors. The number of factors per publication ranged from 1 to 20, with 89 different commonalities proposed in all. Analyses revealed that 41 % of proposed commonalities were change processes; by contrast, only 6% of articulated commonalities were client characteristics. The most consensual commonalities across categories were development of a therapeutic alliance, opportunity for catharsis, acquisition and practice of new behaviors, and clients' positive expectancies. The frequency of selected commonalities is presented and directions for future research are outlined. Mental health professionals have long observed that disparate forms of psychotherapy share common elements or core features (Goldfried Thompson, 1987). As early as 1936, Rosenzweig, noting that all forms of psychotherapy have cures to their credit, invoked the famous Dodo Bird verdict from Alice in Wonderland, Everybody has won and all must have prizes, to characterize psychotherapy outcomes. He then proposed as a possible explanation therapeutic common factors, including psychological interpretation, catharsis, and the therapist's personality. In 1940, Watson reported the results of a meeting held to ascertain areas of agreement among psychotherapy systems (Sollod, 1981). The participants, including such diverse figures as Saul Rosenzweig, Alexandra Adler, Frederick Allen, and Carl Rogers, concurred that support, interpretation, insight, behavior change, a good therapeutic relationship, and certain therapist characteristics were common features of successful psychotherapy approaches (Watson, 1940).