Maternal depressive symptoms (MDS) have been linked to both child internalizing and externalizing behavior problems. Theory suggests that child attachment security may be a protective factor against the negative effects of MDS. This study examined child attachment security as a buffer of the link between MDS and child internalizing and externalizing behavior problems at two time points in a predominantly African American sample. Participants included mothers (N = 164; M age = 29.68 years; 76% African American) and their preschool-aged children (60% girls; M age = 44.67 months) recruited from four Head Start centers in low-income neighborhoods in Baltimore, Maryland. MDS were concurrently associated with child internalizing and externalizing behavior problems at both time points. No significant main effects of child attachment security on behavior problems emerged; however, child attachment moderated the association between MDS and child internalizing behavior problems at Time 2, such that MDS predicted greater child internalizing problems when attachment security was low, and the effect was attenuated when attachment security was high. No interaction emerged for child externalizing problems. Findings suggest that secure attachment in early childhood can serve as a protective factor in the context of parental risk. We discuss implications for intervention and the intergenerational transmission of psychopathology.