In the first part of the experiment all Ss were administered a battery of psychological tests that they were told would provide an accurate description of their personality. Two weeks later, Ss were contacted and asked to participate in the second half of the experiment. Half of the Ss were led to believe that the psychological assessment indicated that they could remain calm and relaxed when exposed to a stressful situation (therapeutic suggestion), while the other half did not receive this feedback (no suggestion). Half of the Ss then were exposed to a stressful situation (threat), while the other half were not (no threat); the effectiveness of the diagnostic predictions was assessed via physiological and self-report measures of arousal. Results indicated that (a) the threat manipulation was effective in creating stress; and (b) Ss given therapeutic-suggestion feedback based on the psychological assessment were able to remain significantly more calm and relaxed in the experiment than Ss who did not receive therapeutic suggestions. Implications for the use of psychological testing and diagnostic feedback as a technique of social influence are discussed.