A large body of literature documents that children of depressed mothers have impaired cognitive, behavioral, and health outcomes throughout the life course, though much less is known about the mechanisms linking maternal depression to children’s outcomes. In this paper, I use data from the Fragile Families and Child Wellbeing Study to estimate and explain the consequences of maternal depression for 5-year-old children’s internalizing and externalizing problem behaviors. Ordinary least squared (OLS) regression models and propensity score models show that children exposed to both chronic and intermittent maternal depression have more problem behaviors than their counterparts with never depressed mothers. Results also show that economic resources and maternal parenting behaviors mediate much of the association between maternal depression and children’s problem behaviors, but that relationships with romantic partners and social support do little to explain this association. This research extends past literature by illuminating some mechanisms through which maternal depression matters for children; by utilizing longitudinal measures of depression; by employing rigorous statistical techniques to lend confidence to the findings; and by using a large, diverse, and non-clinical sample of children most susceptible to maternal depression. Given that early childhood problem behaviors lay a crucial foundation for short- and long-term life trajectories, the social consequences of maternal depression may be far-reaching.