At a meeting of the American Academy of Pediatrics held in 1941, Lawrence Frank presented his ‘General Considerations on Certain Problems of Puberty and Adolescence’. The first half of the 20th century also saw the first attempts to standardise the ‘normal’ workings of young male and female bodies, particularly in view of their nutritional and clinical needs. By 1940, nutritional and metabolic standards for sexually maturing children were an epidemiological priority. In that year, US physician Joseph Johnston entertained a possible relationship between metabolic phenomena and the incidence of tuberculosis, which remained a worrying epidemic. As earlier argued, within the whole mystique around internal secretions, on the one hand, and experimental work on sexual chemistry, on the other, the endocrinal body emerged by the early 1900s. This chemically sexual body, as show, quickly became a central object in the practices and discourses of the modern paediatric science of that century, as well as one of its main technologies of power.