Prospective studies that begin during pregnancy and follow the mothers and children into adolescence have shown that maternal mental illness during the antenatal and postpartum period can have long-lasting negative consequences on the developing child. The findings from these prospective studies and a discussion of the consistencies and inconsistencies in the current literature are presented. The effects of maternal anxiety and depression during the perinatal period on cognitive, behavioral, and psychologic development from infancy through adolescence are examined.