The vast majority of new mothers experience at least some depressive symptoms. Postpartum maternal depressive symptoms can greatly influence children's outcomes (e.g., emotional, cognitive, language, and social development). However, there have been relatively few longitudinal studies of how maternal depressive symptoms may influence children's social skills. The current study (n = 1363) examined the trajectory of maternal depressive symptoms (from 1 month to 36 months) and whether maternal depressive symptoms at 1 month postpartum and the change in symptoms over time (from 1 month to 3 years) predicted children's parent- and teacher-rated social skills when they were 4.5 and 6.0 years old. A growth curve model indicated that, on average, maternal depressive symptoms declined over time in a nonlinear fashion. Further analyses indicated that after controlling for five demographic factors (child sex, family income, maternal age, mother's marital status, and maternal education), initial maternal depressive symptoms significantly predicted children's social skills as reported by mothers. The results support the notion that maternal depressive symptoms during children's infancy can have long-term associations with children's social skills. In addition, the results emphasize the importance of intervention and prevention efforts targeting maternal depressive symptoms during infancy, beginning immediately postpartum.