This article focuses on a review of evidence related to the following 3 questions: (1) Does depression appear during the menopausal transition? (2) What factors influence the risk for depression during the menopausal transition? (3) Do age-related alterations in ovarian hormone secretion contribute to the development of depression in some middle-aged women? A brief background is provided on the importance of depressive disorders. Methodologic issues that have compromised previous studies investigating the possible relation between the menopausal transition and depression are discussed. Evidence is presented that suggests a relation between the perimenopause (the interval between the early menopausal transition and 1 year after the last menses), but not the postmenopause, and the onset of depressive illness. Finally, studies are reviewed that suggest an association between alterations in ovarian function and depression, including several randomized placebo-controlled trials examining the antidepressant efficacy of estradiol in depressed perimenopausal and postmenopausal women.