Depression is a common problem among pregnant andpostpartum women, with rates comparable to or greater than those among women of childbearing age who are not pregnant or postpartum. Perinatal depression is associated with a wide range of unique assessment and treatment complexities, risk factors, and consequences for women and offspring. In this chapter, we review current research on the prevalence of perinatal depression, etiology, risk factors, and consequences, and we discuss assessment strategies and interventions. Limitations to current research and future research directions are noted. We conclude with guidelines for practitioners for assessing and treating depression during the perinatal period.