BACKGROUND: Anxiety and depression are highly prevalent in youth and can cause significant distress and functional impairment. The presence of maternal anxiety and depression are well-established risk factors for child internalizing psychopathology, yet the responsible mechanisms linking the two remain unclear. METHODS: We examined the potential mediating and moderating roles of EEG frontal alpha asymmetry (FAA) in the intergenerational transmission of internalizing symptoms in a longitudinal sample of N = 323 mother-child dyads. Self-report maternal internalizing symptoms were evaluated at child age 3 years and 5 years, child EEG at 5 years, and parent-report child internalizing symptoms at age 7 years. Mediation was evaluated via bootstrapped (N = 5,000) confidence intervals. RESULTS: We found significant associations among maternal internalizing (anxiety, depressive) symptoms when their children were ages 3 and 5 years, child FAA at age 5 years, and child internalizing symptoms at age 7 years. There was a significant mediation effect, whereby greater maternal anxiety and depressive symptoms at age 3 years were significantly associated with FAA (greater relative right cortical activation) in children at age 5 years, which, in turn, was significantly associated with greater child internalizing symptoms at age 7 years (ps <
.001). There was no moderating effect of FAA on the association between maternal internalizing symptoms at age 5 years and child internalizing symptoms at age 7 years. CONCLUSIONS: Greater right frontal asymmetry may be a neurophysiological mechanism that mediates the intergenerational transmission of internalizing symptoms.