This quantitative study investigated the effect of client self-disclosure on the physiological arousal of the therapist and subsequent ratings of the therapeutic alliance, session smoothness, and session depth. Three therapists and 10 clients participated in a 40-minute videotaped therapy session while being attached to sensors that measured heart rate and skin conductance. The participants completed self-report questionnaires designed to assess the therapeutic alliance and session smoothness and depth immediately following the therapy session. The videotaped therapy sessions were later transcribed and coded by two independent coders for the occurrence of client self-disclosure. Correlation analyses were utilized to determine whether or not a relationship existed between client self-disclosure and the physiological arousal of the therapist. No significant relationships were found to exist between client self-disclosure and the physiological arousal of the therapist. Positive correlations were found to exist between the occurrence of client self-disclosure and the physiological arousal of the therapist as well as between the occurrence of client self-disclosure and the therapeutic alliance. The physiological arousal of the therapist was also found to be positively correlated with the strength of the therapeutic alliance.