Though sociologists have examined how mass incarceration affects stratification, remarkably little is known about how it shapes educational disparities. Analyzing the Fragile Families Study and its rich paternal incarceration data, I ask whether black and white children with fathers who have been incarcerated are less prepared for school both cognitively and non-cognitively as a result, and whether racial and gendered disparities in incarceration help explain the persistence of similar gaps in educational outcomes and trajectories. Using a variety of estimation strategies, I show that experiencing paternal incarceration by age five is associated with lower non-cognitive school readiness. While the main effect of incarceration does not vary by race, boys with incarcerated fathers have substantially worse non-cognitive skills at school entry, impacting the likelihood of special education placement at age nine. Mass incarceration facilitates the intergenerational transmission of male behavioral disadvantage, and because of the higher exposure of black children to incarceration, it also plays a role in explaining the persistently low achievement of black boys.