This paper presents how the medico-hygienist model of childhood, which had prevailed throughout the nineteenth century, was replaced at the turn of the twentieth century by the novel developmental model, which arose in the first decades of the 1900s and was later systematised by Piaget, Spock, etc. The medico-hygienist model revolved around core constituents such as regulation, firmness and discipline, standardisation whose historical specificity could be, according to Elias, related to the civilising process. The developmental model, on the other hand, is linked to the systematic scientific investigation of childhood and pertains, foremost, to the proposition that growing up was best figured in the concept of development: the figure of the child as a human who develops consistently in time and space. The key element can be worded as follows: Why is such child maturation almost universally constructed as development? The second crucial idea of the model consists in understanding child development in terms a (rather linear) sequence of particular stages. The equation of child maturation, both physically and psychologically, with development is crystallised in the figure of a uniform, inevitable and universal sequence of developmental stages and, accordingly, its schedule; therefore, maturation, development, stages and sequences are closely connected to children's socialisation. My aim is to trace developmental thinking in its historical specificity by bringing to light some neglected social processes that contribute to the regulation of children and the transformation of generational relationships. These processes have always occurred in various societies, and yet I am trying to put forward an original perspective that pertains to the intersection of developmental thinking and social change. I attempt here to introduce a historic juncture of developmental thinking and social transformations that moulded children. I also attempt to track down the historical roots of the developmental framework: how it became the central principle by which we think about children today.