Premenstrual dysphoric disorder, which affects 2%–5% of premenopausal women, was included in Appendix B of DSMIV, "Criterion Sets and Axes Provided for Further Study." Since then, aided by the inclusion of specific and rigorous criteria in DSM-IV, there has been an explosion of research on the epidemiology, phenomenology, pathogenesis, and treatment of the disorder. In 2009, the Mood Disorders Work Group for DSM-5 convened a group of experts to examine the literature on premenstrual dysphoric disorder and provide recommendations regarding the appropriate criteria and placement for the disorder in DSM-5. Based on thorough review and lengthy discussion, the work group proposed that the information on the diagnosis, treatment, and validation of the disorder has matured sufficiently for it to qualify as a full category in DSM-5. A move to the position of category, rather than a criterion set in need of further study, will provide greater legitimacy for the disorder and encourage the growth of evidence-based research, ultimately leading to new treatments.