The current study examined the interaction between maternal depressive symptoms and child temperament in predicting subsequent child language skills. Participants were 252 mother-child dyads recruited from the All Our Families longitudinal cohort, a primarily middle-class sample (62.9% completed postsecondary education) from Alberta, Canada (90.5% White, 6% Asian, 3.5% other). Maternal depressive symptoms at age 3, controlling for prenatal depressive symptoms, did not evidence a direct effect on child language skills at age 5 (49.6% males; mean [M] = 5.12 years old, standard deviation [SD] = 0.11). However, both child surgency and effortful control interacted with maternal depression at age 3 to predict later language skills. Low effortful control was a risk factor for poorer language abilities in contexts of high maternal depressive symptoms. High child surgency emerged as a differential susceptibility marker, predicting poorer language skills in contexts of high maternal depressive symptoms but better language skills in contexts of low depressive symptoms. Negative affect did not interact with maternal depressive symptoms in predicting language skills. These findings highlight the complex interaction between maternal and child characteristics in predicting language development during a developmental period in which language skills are a prime indicator of school readiness and a predictor of future academic achievement and socioemotional adjustment.