Drawing on medical advice literature, this paper examines the cultural history of the body in infancy in eighteenth-century England. This period saw the increasing professionalization of the medical field, particularly regarding children’s health, as an emerging profession of educated, male physicians sought to establish their exclusive authority on the medical market. As England’s medical market of the time was largely unregulated, these educated physicians competed with apothecaries, midwives, and female nurses for paying customers. Physicians argued that the disorderly, undisciplined nature of the infant body was incongruent with Enlightenment virtues, and therefore required a greater degree of medical management. Emerging out of this discourse were popular advice books which emphasized preventative measures in already-healthy infant patients. They were authored by a growing profession of educated, medical experts and were addressed to a lay audience of parents and child caretakers. This paper examines three immensely popular pamphlets authored by three physicians, Thomas Beddoes, George Armstrong, and William Cadogan. All three emphasized in their tracts the importance of maternal breastfeeding to the infant diet, citing Enlightenment ideals, humoral theory, and even the supernatural elements of breastmilk to support this claim. To bring the child body firmly under the control of the medical establishment, they argued that uneducated, lay practitioners, who were overwhelmingly female, received no formal education in the sciences and thus possessed little understanding of the nuances and complexities specific to the infant body. Parents were also incapable and deficient, at least to some degree, in the formal knowledge necessary to prevent illness in their infant children, and thus should rely on the physician’s expertise regarding the care of the infant body.