Educational inequality in the health of U.S. children—what social scientists refer to as the “educational gradient” in health—is present at birth for virtually every marker of health, and increases throughout childhood. However, a puzzling contradiction to this pattern has been observed among the growing population of youth in immigrant families. Some evidence suggests an ambiguous relationship between education and health among immigrant families, with a flat relationship between maternal education and maternal health behaviors and children’s birth outcomes, and a stronger relationship as children become adolescents. Does an educational gradient in health emerge among children in immigrant families during childhood and adolescence? To date, we lack a prospective examination of how the gradient changes from birth throughout childhood and adolescence among this population. Moreover, while the dominant explanation for a weaker gradient among children with immigrant parents centers on the family setting, we know little about family-level dynamics among the same immigrant families as children age. Using national, longitudinal data from the Fragile Families and Child Well-Being Study, we examine the association between maternal education and children’s health (measured by mothers’ ratings) over the early life course (birth through age 15) among children of immigrants and children of native-born parents, and consider whether changes in children’s economic status and family composition contribute to the educational gradient, or lack thereof, in child health. Analyses reveal that: (1) maternal education is strongly predictive of health, even among children of immigrants; (2) immigrant status does not appear to be protective for health within educational groups, as evidenced by poorer health among children of immigrants whose mothers have the lowest level of education, as compared to children of natives; (3) children in the least-educated immigrant families are experiencing better health trajectories as they age than children in similar native-born families; and (4) accounting for economic conditions and family composition does not reduce the size of the gradient over time.