Donald Seldin from The University of Texas Southwestern Medical School joins the JCI for its Conversations with Giants in Medicine. Seldin served as the chairman of medicine at UT Southwestern for nearly four decades and transformed the department and the school from a grouping of ramshackle army barracks to a world-class medical center, host to Nobel Laureates and members of the national academies. He was also a major figure in the emergence of nephrology as a legitimate discipline, and in this role he was one of the founders of the American Society of Nephrology and served as its second president. Among his many attributes, Seldin has been described as one of the most magnetic and charismatic mentors academic medicine has encountered.