China's one-child-per-couple policy represents an extraordinary attempt to engineer national wealth, power, and global standing by drastically braking population growth. Despite the policy's external notoriety and internal might, its origins remain obscure. In the absence of scholarly research on this question, public discourse in the United States has been shaped by media representations portraying the policy as the product of a repressive communist regime. This article shows that the core ideas underlying the one-child policy came instead from Western science, in particular from the Club of Rome's world-in-crisis work of the early 1970s. Drawing on research in science studies, the article analyzes the two notions lying at the policy's core—that China faced a virtual “population crisis” and that the one-child policy was “the only solution” to it—as human constructs forged by specific groups of scientists working in particular, highly consequential contexts. It documents how the fundamentally political process of constituting population as an object of science and governance was then depoliticized by scientizing rhetorics that presented China's population crisis and its only solution as numerically describable, objective facts. By probing the human and historical character of population research, this article underscores the complexity of demographic knowledge-making and the power of scientific practices in helping constitute demographic reality itself.