Pediatric endocrinology evolved as a subspecialty from the era of biochemical and metabolic clinical investigation led by John Howland, Edwards Park, and James Gamble at Johns Hopkins; Allan Butler at Boston University and Harvard University; Daniel Darrow at Yale University; and Irving McQuarrie at the University of Rochester and the University of Minnesota during the early 20th century. The father of the new subspecialty was Lawson Wilkins, a private pediatric practitioner in Baltimore, Maryland, who was invited by Dr. Edwards Park to establish an endocrine clinic at the Harriet Lane Home at Johns Hopkins in 1935. Dr. Wilkins managed his practice and the clinic until 1946, when, at the age of 52, he accepted a full-time position at the University. Dr. Nathan Talbot was invited to develop a pediatric endocrine clinic at Massachusetts General Hospital by Allan Butler in 1942. These units and their associated subspecialty training programs during the 1950s and 1960s provided the large majority of the second-generation pediatric endocrinologists who went on to establish endocrine subspecialty programs in university medical centers in North America as well as Europe and South America. Diabetes as a clinical pediatric discipline evolved in parallel from the early clinics of Elliott Joslin and Priscilla White in Boston, M.C. Hardin and Robert Jackson at the University of Iowa, George Guest at the University of Cincinnati Children's Hospital, and Alex Hartman at the St. Louis Children's Hospital. The Lawson Wilkins Pediatric Endocrine Society was founded in 1971, and the Council on Diabetes and Youth was established within the American Diabetes Association in 1980. Medical and economic factors led to increasing integration of pediatric diabetes and general endocrine care and training, and diabetes care now is a major activity within the subspecialty of pediatric endocrinology. The growth of pediatric endocrinology in North America has paralleled the growth of academic medicine during the past half-century. In 2002, there were 72 training programs in North America: 65 in the United States and seven in Canada. The endocrinology sub-board of the American Board of Pediatrics was established in 1978 to certify training and competence in endocrinology, including diabetes. By 2002, the board had certified 927 pediatric endocrinologists. Pediatric endocrine subspecialists during the past half-century have contributed major advances in our understanding of the ontogeny of endocrine systems and the diagnosis and treatment of fetal-perinatal endocrine disorders; newborn screening for endocrine and metabolic disorders; the physiology and therapies for disorders of sexual differentiation and pubertal maturation; the development of anthropometric standards for childhood growth and development; the characterization and physiology of hormone systems, including receptors and hormone actions; the molecular genetics of a number of congenital endocrine disorders and heritable endocrine diseases; development of pediatric endocrine diagnostics and reference standards; the pathophysiology and management of autoimmune endocrine disease; and development of a growing armamentarium of therapeutic agents for treatment of endocrine and metabolic diseases.