Self-disclosure (SD) is considered an important part of psychotherapy and an essential ingredient of psychological health. The difference between self-reported SD (how much a patient said he disclosed) and observed SD (how much a therapist said the patient disclosed) was investigated to examine the effects on psychotherapy outcome. Adult psychiatric inpatients (N=43) were divided into therapy groups of six to 10 patients meeting eight times in a two-week period. Patients completed the Group Therapy Self-Disclosure Questionnaire and observers rated self-disclosure using the Rating Scale Guideline. Results indicated that self-reported SD measures were not valid instruments to assess the SD of certain patients. Subjects were divided into three categories of SD discrepancy: overraters, concordants, and underraters. Overraters also overrated their own outcome. Underraters and concordants agreed with the therapists about their outcomes. Underraters and concordants were most likely to be neurotic and depressed, while the overraters were more likely to be psychotic. (NRB)