Little is known about which processes explain the well-established link between maternal and child symptomatology. Interpersonal coping processes may be worth exploring, as depressed mothers have characteristic coping styles that may influence interactions with their children. We examined two interpersonal coping processes as potential factors explaining how depressive symptomatology in mothers impacts child psychopathology: parent-child co-rumination (dwelling on negative affect, over-analyzing problems) and impaired problem-solving. We analyzed 198 aggressive children (most of whom also had elevated internalizing symptoms) who engaged in structured discussions with their mothers. Coders rated the extent to which dyads problem-solved and co-ruminated during discussions, and mothers filled out questionnaires assessing maternal and child symptoms. Path analysis tested whether higher levels of co-rumination and poor problem-solving statistically mediated the relation between depressive symptoms in mothers and child internalizing and externalizing behaviour. Maternal depressive symptomatology was correlated with greater child symptoms, higher rates of co-rumination and poorer problem-solving. Statistical mediation was non-significant. Results support the established link between maternal depression and child psychopathology, and suggest that dysphoric mothers and their children engage in maladaptive coping interactions.