Until well into the 1800s, what mostly concerned and fascinated the clinical profession about puberty was the monstrous manifestation of its ‘signs’ on the body of the infant and the young child. Confronted with the child monster’s natural-unnatural condition, doctors in the 1800s expressed concerns which, while in line with the general alarm regarding child mortality, were also distinct from the traditional medical preoccupation about infants’ survival and safeguarding childhood. Alongside anxieties about reproductive, pubertas praecox raised the associated problem of how to educate and morally guide the child monster towards adulthood. These psychosocial questions were central to the formation of modern puberty science, as they provided the point of contact between monstrosity and abnormality in 19th-century clinical views of the condition. In child monstrosity discourse, this analytical framework served either to normalise and even praise or disqualify the child’s intellectual faculties.