PROBLEM Leitenberg, et aE. ( 3 ) , and Oliveau, et al. ( 6 ) have reported experiments which, cumulatively, suggest that the beneficial effects of systematic desensitization depend on knowledge that one is "in therapy." Snake-avoidant Ss who experienced desensitization operations but who were unaware of the presumed therapeutic value of them did not benefit to the same degree as did Ss who knew that the operations were intended to be therapeutic. McGlynn, Reynolds and Linder (6) reported an experiment in which a similar instructional manipulation had no impact on the outcome of desensitization operations. Mouse-avoidant Ss who were told that the Es were studying physiological reactions improved to the same extent as did Ss who were told that the Es were studying a therapeutic technique. While