The Distress Disclosure Index (DDI; J. H. Kahn & R. M. Hessling, 2001) is a brief self-report measure of one's tendency to disclose personally distressing information. The purpose of this article was to summarize what is known about the DDI, present new validity evidence, and make recommendations for use of the DDI. This article reviews research on the DDI from the past decade that indicates that distress disclosure is associated with well-being, professional help-seeking attitudes and intentions, and success in brief psychotherapy. On the basis of the reviewed literature, the authors report a reliability generalization study of DDI scores that strongly supports the internal consistency and test-retest reliability of DDI scores, and they review criterion-related and construct validity evidence. Next, the authors present a new multitrait-multimethod validity study of the DDI. Participants (N = 153) and peer informants (N = 153)--one per participant--completed paper-and-pencil questionnaire packets. Convergent validity of self-reported DDI scores was supported by a strong association with self-reports of emotional self-disclosure in response to a specific, unpleasant event, and self- and peer reports on the DDI were moderately correlated. DDI scores were not strongly associated with cognitive reappraisal and ambivalence over emotional expression, thus supporting discriminant validity. DDI scores were strongly associated with expressive suppression, and correlations between DDI scores and affect, depression symptoms, coping, and emotional expressivity were similar to those found with expressive suppression. The authors offer possible hypotheses explaining the overlap between distress disclosure and expressive suppression and present recommendations for future use of the DDI. (Contains 1 figure and 6 tables.)