This article uses data from the Fragile Families and Child Well-Being Survey (N = 2,427) to examine the association between the chronicity and timing of maternal depression and child well-being. Maternal depression, particularly chronic depression, is linked to internalizing and externalizing problem behaviors in children, and children have worse behaviors when mothers report proximate depression. Children of depressed and nondepressed mothers have similar cognitive outcomes. Results also suggest that boys are more vulnerable to maternal depression than girls and that socioeconomic advantage does not buffer children from the consequences of maternal depression. Given that impairments in early childhood may place children on disadvantaged life-course trajectories, early intervention and treatment of depressed mothers may help ameliorate social disparities. (Contains 4 tables.)