Many believe that increasing the quantity of children will lead to a decrease in their quality. This paper exploits plausibly exogenous changes in family size caused by relaxations in China's One Child Policy to estimate the causal effect of family size on school enrollment of the first child. The results show that for one-child families, an additional child significantly increased school enrollment of first-born children by approximately 16 percentage-points. The effect is larger for households where the children are of the same sex.