I am currently investigating how a variety of factors affect the initial development of premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) in two studies of premenopausal women. PMS and PMDD affect up to 20% of reproductive age women and are associated with levels of impairment comparable to those of other major affective disorders. The most common symptoms of PMS and PMDD include irritability, mood swings, anxiety, depression, breast tenderness, bloating, and headaches in the luteal phase of the menstrual cycle. While many pharmaceutical treatments for PMS and PMDD have been evaluated, all have significant limitations and none has a reported efficacy greater than 60-70%. Because of the substantial limitations of available treatments, it is important to identify ways to prevent the initial development of these disorders.