Most of China’s fertility decline predates the famous One Child Policy—and instead occurred under its predecessor, the Later, Longer, Fewer (LLF) policy. Studying LLF’s contribution to fertility and sex selection behavior, we find that it i) reduced China’s total fertility rate by 0.9 births per woman (explaining 28% of China’s modern fertility decline), ii) doubled the use of male-biased fertility stopping rules, and iii) promoted postnatal neglect (implying 210,000 previously unrecognized missing girls). Considering Chinese population policy to be extreme in global experience, this paper demonstrates the limits of population policy—and its potential human costs.