Background: Building on reports that parental maltreatment and neglect adversely affect young children's executive function (EF), this longitudinal study examined whether exposure to a more common risk factor, mothers' depressive symptoms, predicted individual differences in EF at school-age. Methods: We followed up at age 6 a socially diverse sample of 126 children (78 boys, 48 girls) for whom direct observations of mother-child interactions have been shown to predict gains in EF between the ages of 2 and 4. We used an EF latent factor based on scores from three tasks (Beads, Day/Night, Tower of London) that tapped working memory, inhibitory control and planning, as well as a latent growth model of mothers' Beck Depression Inventory factor scores at four time-points, and included age 6 verbal ability as a covariate in all analyses. Results: The intercept and slope for mothers' depressive symptoms each predicted unique variance in EF at age 6; these predictive effects remained significant when we also included: (a) age 2 working memory, (b) maternal education and (c) direct observations of maternal positive control at ages 2 and 6. Conclusion: Our findings suggest that early exposure to mothers' depressive symptoms adversely affects children's developing EF, and that the chronicity of this exposure may matter. (Contains 4 figures and 3 tables.)