||In 2012, CDC researchers found that 11.5% of women delivering a live birth that year had postpartum depressive symptoms (Ko, Rockhill, Tong, Morrow, & Farr, 2017). Children who have been exposed to maternal depressive symptoms in their first year of life tend to show elevated deficits in a variety of domains later in life. However, not all children exposed to maternal depression exhibit these deficits, suggesting the presence of a moderator. The present study examines whether exposure to maternal depression at 4 months predicts behavioral problems at 3 years. The role of maternal sensitivity, measured at 1 month, was evaluated as a moderator of this association. We analyzed data from a sample of 1,388 mother-infant dyads with prenatal substance exposure from the Maternal Lifestyle Study. Dyads were followed from 1 to 36 months of age. We found that more symptoms of maternal depression at 4 months were positively correlated with more problem behavior in preschoolers at 3 years. Mothers who had high levels of depressive symptoms and who engaged in more stimulation when interacting with their infants had preschoolers with problem behavior scores similar to preschoolers of mothers with lower levels of depressive symptoms. The other subscales of maternal sensitivity did not significantly moderate the effects of maternal depression on preschool problem behavior. Within the context of high rate of maternal depression, these findings support targeting maternal sensitive behaviors, particularly those within the domain of stimulation, for early intervention to provide infants with the best possible resources as they develop.