Although parents and children are thought to influence one another’s affect and behavior, few studies have examined the direction of effects from children to parents, particularly with respect to parental psychopathology. We tested the hypothesis that children’s affective characteristics are associated with the course of mothers’ depressive symptoms. Children’s affect expression was observed during a series of mother–child interaction tasks, and children’s resting frontal electroencephalogram (EEG) asymmetry was assessed in a psychophysiology laboratory. Mothers’ depressive symptoms were assessed at two time points, approximately one year apart, at the mother–child interaction visits. Depressive symptoms increased over time for mothers with a history of childhood-onset depression whose children exhibited right frontal EEG asymmetry. Depressive symptoms were associated with high child negative affect at both time points for mothers whose children exhibited right frontal EEG asymmetry. Cross-lagged models with a subset of participants provided some evidence of both parent-to-child and child-to-parent directions of effects. Findings suggest that akin to other interpersonal stressors, children’s affective characteristics may contribute to maternal depressive symptoms.