Premenstrual Dysphoric Disorder (PMDD) is characterized by cyclical affective core symptoms accompanied by additional psychological and somatic symptoms that are confined to the luteal phase of the menstrual cycle. The etiology of PMDD is not fully understood. Multifactorial approaches posit that biological, social, and psychological factors contribute to the development and maintenance of PMDD. Rumination, a transdiagnostic risk factor for mental disorders, may particularly contribute to premenstrual symptom severity in PMDD. This chapter presents the clinical manifestation of PMDD and reviews findings on the role of rumination in the psychopathology, the development, and the maintenance of PMDD. Recommendations regarding treatment options for PMDD are summarized, and possible novel psychotherapeutic approaches to address rumination in PMDD are discussed. Finally, applications of the reviewed findings on rumination and PMDD to premenstrual exacerbations of other ongoing mental disorders are outlined.