Perinatal depression, which includes major and minor depressive episodes that occur during pregnancy or in the first 12 months after delivery, is one of the most common medical complications during pregnancy and the postpartum period, affecting one in seven women. It is important to identify pregnant and postpartum women with depression because untreated perinatal depression and other mood disorders can have devastating effects on women, infants, and families. Several screening instruments have been validated for use during pregnancy and the postpartum period. Although definitive evidence of benefit is limited, the American College of Obstetricians and Gynecologists recommends that clinicians screen patients at least once during the perinatal period for depression and anxiety symptoms using a standardized, validated tool. Although screening is important for detecting perinatal depression, screening by itself is insufficient to improve clinical outcomes and must be coupled with appropriate follow-up and treatment when indicated; clinical staff in obstetrics and gynecology practices should be prepared to initiate medical therapy, refer patients to appropriate behavioral health resources when indicated, or both.