This essay explores the social processes surrounding the creation of knowledge about children's medicine in early modern England. Looking first at printed volumes on children's health by male authors, the essay shows that the men who were the first to print texts about children's medicine recommended, replicated and authorized women's knowledge in the field, even as they also constructed women as subordinate observers. The essay then takes up the question of how women constructed authority for themselves in domestic medicine by looking at the affinities of women's knowledge practices with learned medicine, particularly their investment in observation and proof. The essay concludes with an examination of rickets, which exemplifies the key role of women in knowledge formation around children's diseases. It shows how women's experiential knowledge and domestic practices provided a largely unacknowledged influence on one of the first learned texts on rickets, A Treatise of the Rickets (1651).