This chapter examines the development of modern population statistics, c.1860s–1910s. It describes the institutionalization of population statistics in Japan, first in tandem with the making of a modern official administration in the 1860s–1880s, and, from the 1890s, alongside colonial rule of Taiwan. It explores how the emerging cohort of individuals centering around bureaucrat Sugi Kōji established a scientific community, by taking advantage of their positions within the new government. At the same time, it depicts these modern statisticians’ coterminous position to political authority did not automatically grant them power to implement the scientific practices for which they lobbied. It illustrates this point by exploring their campaign to implement a national census in Japan. The chapter also shows how statisticians campaign came to fruition not in the metropole, but initially in the context of Japan’s colonial rule over Taiwan. Gotō Shinpei, a high-ranking officer in colonial Taiwan, promoted a population census, deeming it a valuable tool for scientific colonial governance. Finally, this chapter examines the activities of Mizushina Shichisaburō to describe how the scientific practice and community thrived in Taiwan surrounding the census work, and how the Taiwanese experience ultimately fed back to the statistical activities in the metropole.