Statistically, women, particularly pregnant women and new mothers, are at heightened risk for depression. The present review describes the current state of the research linking maternal depressed mood and children's cognitive and language development. Exposure to maternal depressive symptoms, whether during the prenatal period, postpartum period, or chronically, has been found to increase children's risk for later cognitive and language difficulties. The present review considers both the timing of maternal depression and the chronicity of mothers' depression on children's risk for cognitive and language delays. Infancy is frequently identified as a sensitive period in which environmental stimulation has the potential to substantially influence children's cognitive and language development. However, children's exposure to chronic maternal depression seems to be associated with more problematic outcomes for children, perhaps because depression interferes with mothers' ability to respond sensitively and consistently over time. Consistent with this expectation, interventions targeting parenting practices of depressed mothers have been found to increase children's cognitive competence during early childhood. The current review provides a synthesis of the current state of the field regarding the association between maternal depression and children's cognitive and language development during early childhood.