Despite considerable controversy in the field about the value of clinical trials research (cf. Strupp 1980; Parloff 1981) the public, government, insurance companies, and to a great extent the field itself have been increasingly concerned with the efficacy of psychotherapy. Clinicians and many psychotherapy researchers today agree that the answer to the question "Is psychotherapy effective?" is "yes' (Garfield 1983; Smith et al. 1980). Nevertheless we have made little advance in answering the question which Paul (1967, p. 111) posed: "What treatment, by whom, is most effective for this individual with that specific problem, and under which set of circumstances?" (see Stiles et al. 1986).