This paper measures the effect of China’s one-child policy on fertility by exploring
the natural experiment that has been created by China’s unique affirmative birth control
policy, which is possibly the largest social experiment in human history. Because
the one-child policy only applied to Han Chinese, but not to ethnic minorities, we
construct a differences-in-differences estimator to identify the effect of the policy on
fertility. Such a natural experiment is a rare opportunity, whether for the analysis of
the effect on fertility or for the analysis of economics in general. Using two rounds
of the Chinese Population Census, we find that the one-child policy has had a large
effect on fertility. The average effect on the post-treatment cohorts on the probability
of having a second child is as large as -11 percentage points. We also find that the
magnitude is larger in urban areas and for more educated women. Our robustness tests
suggest that our differences-in-differences estimates of the effect of the one-child policy
are not very likely to be driven by other policy or socio-economic changes that have
affected the Han and the minorities differently.