Using the British Household Panel Survey, we investigate if family size and birth order affect children's subsequent educational attainment. Theory suggests a trade-off between child quantity and "quality" and that siblings are unlikely to receive equal shares of parental resources devoted to children's education. We construct a new birth order index that effectively purges family size from birth order and use this to test if siblings are assigned equal shares in the family's educational resources. We find that the shares are decreasing with birth order. Ceteris paribus, children from larger families have less education, and the family size effect does not vanish when we control for birth order. These findings are robust to numerous specification checks.