Pediatrics arose as an academic and medical specialty in the United States during the late nineteenth century. This paper documents the first three stages of academic pediatrics in the United States between 1850 and 1950: (1) 1850-1880, a period focused on sanitary reform as a means of reducing infant mortality; (2) 1880-1900, the era where discoveries being made in bacteriology, physiology, and nutrition began to be applied to improving the health of children; and (3) 1900-1930, when the field was characterized by an active health reform movement directed at parents and health care professionals. Three prominent pioneer pediatricians, Drs. Abraham Jacobi, Henry Koplik, and L. Emmett Holt, are profiled as representative practitioners of these eras.