Dr. Karl D. Nolph is widely recognized as one of the pioneers of modern peritoneal dialysis and a central figure in the evolution of nephrology over the past half century. Joining the University of Missouri in 1969, he helped transform the institution into an internationally respected center for dialysis research, education, and patient care. Through his groundbreaking investigations of peritoneal membrane physiology, his leadership in the development and evaluation of continuous ambulatory peritoneal dialysis (CAPD), and his longstanding commitment to home-based therapies, Dr. Nolph shaped the care of countless patients with kidney failure around the world. In this oral history interview, he reflects on his early training, the formative years of dialysis and transplantation, the emergence of CAPD as a transformative therapy, and the individuals, institutions, and ideas that helped define modern nephrology.