Greater emotion regulation capacity in early childhood has far-reaching implications for later adjustment, including better social skills, more successful relationships with friends and families, greater academic achievement, and psychological well-being (Penela et al., 2015). We attempt to further the understanding of familial influences on child emotional development by incorporating insights from children’s moment-to-moment emotional expressions. We used the multilevel Cox proportional hazard model to answer these questions: Does maternal depression predict faster transitions into and slower transitions out of negative emotion displays (i.e., shorter latencies and longer durations), when young children are faced with a frustrating task? Is the effect different for boys and girls? Data were drawn from a larger longitudinal study of 126 mother-child dyads conducted in a Midwestern U.S. city focusing on preschool socioemotional adjustment from 3 to 5 years old. Mothers completed the 21-item Beck Depression Inventory (Beck et al., 1996) to measure the severity of depressive symptomatology. Children’s emotional displays during the Attractive Toy in the Transparent Box task were recorded and coded second-by-second with Observer®. The results from multilevel Cox Regression models for latencies and durations of emotion displays showed that child gender moderated the association between maternal depressive symptoms and latencies of child emotion displays—for both anger (b3 = -.091; SE = .044, p = .037) and sadness (b3 = -.079; SE = .038; p = .037). For girls, higher levels of maternal depressive symptoms were associated with faster transitions into anger and sadness; whereas for boys, higher levels of maternal depressive symptoms were associated with slower transitions into anger and sadness. The latencies of anger and sadness were in general shorter for boys compared with girls, but only when mothers were not depressed. Children of depressed mothers display average speed in transitions to anger and sadness regardless of child sex.