Sexual science constitutes the empirical study of sexual function and behavior in living beings. It originated from natural philosophy and is now characterized by the methods and aims of modern science. This chapter treats the main story of sexual science, starting with conceptual concerns over the body and using examples from Chinese and Islamic medicine. Next, the analysis shifts to the foundations of sexual science in the Western world, examining philosophical and medical traditions that culminated in medieval scholasticism and institutions like universities and hospitals. The chapter then treats the Scientific Revolution and the Enlightenment, in which contemporaries invented the “two-sex” model and pioneered new ideas of “biopolitics.” The analysis turns the nineteenth century’s complex “discovery” of sex and the powerful connections between global imperialism and sexual understanding. The chapter concludes with the dynamics surrounding the body and sexuality in the global twentieth century, as found in evolutionary biology, sexology, and psychoanalysis, and the relation between mass culture and ideals of the sexual revolution. Sexual science appears paradoxical: sometimes, it seemed an agent of discipline and power, supporting entrenched values, or it seemed to help emancipate individuals, debunking prejudices and superstitions and liberating attitudes and behaviors.