Children with a parent who suffers from depression are more likely to develop internalizing problems themselves. Moreover, poverty is an additional risk factor for child internalizing problems. According to models of intergenerational transmission of depression, various environmental mechanisms may account for this transmission. However, very few studies have included multiple mediators, as well as both parents in low-income samples. In this study of low-income families, we measured parental depressive symptoms, child internalizing problems, and examined three potential mediators: parent-child interaction quality, spouse's depressive symptoms, and coparenting conflict. Results indicated that the transmission of paternal depressive symptoms to child internalizing problems was entirely accounted for by these three mediators. The transmission of maternal depressive symptoms to child internalizing problems was mediated partially by coparenting conflict, but this link remained largely direct. These results underscore the need to consider both parents and coparenting conflict in clinical interventions targeting internalizing problems among preschoolers.