Many children grow up with adult alcohol misuse in the home. A clearer understanding of this exposure's long-term mental health consequences and the role of associated child maltreatment experiences and potential protective factors could guide relevant intervention strategies.To prospectively evaluate the association between living with adult alcohol misuse during childhood and major depressive disorder (MDD) during adulthood; whether child maltreatment explains the association; and whether sex, school bonding, or neighborhood bonding moderate the association.At grade 9, participants were asked whether they lived with adults who misused alcohol. Diagnostic assessments of MDD were conducted across three time-points during participants' thirties and participants were categorized as having met diagnostic criteria 0, 1, or 2 or more times.Ordinal logistic regressions found that children living with adult alcohol misuse showed greater chronicity of adult MDD (OR = 1.63; 95% CI: 1.05, 2.52). There was a 49% reduction in the odds ratio and the association was no longer statistically significant when child maltreatment was included in the model (OR = 1.32; 95% CI: 0.84, 2.07). No statistically significant moderation of associations was observed.Children exposed to adult alcohol misuse, and maltreatment often associated with this misuse, may be at risk for mental health challenges well into adulthood. Interventions that address childhood exposure to adult alcohol misuse and associated maltreatment may be important to mitigate long-term mental health challenges to exposed children.