Never-married motherhood is associated with worse educational outcomes for children. But this association may reflect other factors that also determine family structure, rather than causal effects. We use incarceration rates for men as instrumental variables in estimating the effect of never-married motherhood on the high school dropout rate of black and Hispanic children. We find that unobserved factors drive the negative relationship between never-married motherhood and child education, at least for children of women whose marriage decisions are affected by incarceration of men. For Hispanics we find evidence that these children actually may be better off living with a never-married mother. (Contains 38 footnotes, 11 tables, and 3 figures.)