The therapist as a neglected variable in psychotherapy research.

Research on psychotherapy has increased in both quantity and quality over the past 30 years and has tended to focus on the evaluation of outcome. The major emphasis has been on studies comparing different forms of psychotherapy. The recent emphasis on training manuals has reinforced this pattern. On the other hand, the importance of the therapist's contribution to outcome and the related matter of therapist variability have been given inadequate attention. These issues are discussed and evaluated in the articles that follow.