Background: Maternal depression is common, and a known risk for negative child development, including behavior problems. However, many children of depressed mothers do not develop behavior problems, and identifying children at greater risk could increase understanding of the mechanisms involved and improve health interventions. Objectives: The present study aims to investigate three theoretically proposed child characteristics (gender, temperament and inhibitory control) as potential moderators of the empirically established association between maternal depressive symptoms and child behavior problems (internalizing and externalizing problems). Methods: The present study utilizes data from PhD Tone Kristine Hermansen’s doctoral project, which is based on participants from The Norwegian Mother and Child Cohort Study (MoBa). A sample of 96 mothers and their children (mean age 5.7 years, 49 girls) were assessed using self-report measures of concurrent maternal depressive symptoms (BDI-II), child temperament (EAS) and child internalizing and externalizing problems (CBCL). The children also completed a Flanker task as a measure of inhibitory control. The data was analyzed by conducting a series of hierarchical multiple regression analyses. Results: In line with prediction, higher levels of concurrent maternal depressive symptoms were found to predict higher levels of both child internalizing and externalizing problems. Child inhibitory control was found to moderate these associations so that lower levels of inhibitory control predicted a stronger association between concurrent maternal depressive symptoms and both child internalizing and externalizing problems. No moderation effects were found for child gender or temperament. Conclusion: The findings support the notion that maternal depression poses a risk for negative child development. Further, children with poorer inhibitory control seem to be more vulnerable to the negative effects of maternal depression.