Dr. Mavis Kelsey’s career spanned some of the most astounding years ever in the development of medicine as a profession. Medical research and technological developments fundamentally transformed the treatment of patients during those years, but perhaps as important was the transformation of what has come to be called the patient-care delivery system. One of the pioneers of multi-specialty clinics, Kelsey was a founder of the prominent Kelsey-Seybold Clinic in Houston. His story is quintessentially the story of how medicine developed from a single-doctor, home-visit practice to the mega-business, high-tech system it now is, especially in urban areas. Mavis Kelsey’s training included general medical education at the University of Texas in Galveston, internship at Bellevue Hospital in New York, work on staff at Scott and White in Temple, and a residency at the Mayo Clinic, where he was impressed by the benefits of the clinic organization. After serving in World War II, he returned to Rochester to join the staff and participate in the innovative studies then being done at the Mayo, becoming particularly involved with research on metabolic disorders and the use of radioiodine tracers in diagnosing them. As a specialist in endocrinology, Kelsey moved to Houston in 1949, just a few years after contruction began on the Texas Medical Center. With two partners, William D. Seybold and William V. Leary, he welcomed the challenge and opportunity of an ambitious medical environment within one of the country’s fastest growing urban populations and founded the now-famous Kelsey-Seybold Clinic. The years of his practice included the development of an intricate business and professional structure linking the Texas Medical Center with private specialists in Houston, the emerging structure of contract-medicine providers for corporations and institutions (including for the Kelsey-Seybold Clinic, Pennzoil and NASA), and the formation of charitable and research foundations based in the wealth generated by medical practice. In understated but compelling prose, Kelsey brings to life this period of unparalleled challenge and growth in the pioneering Houston medical community. Through anecdotes and memories backed by careful notes he took at the time, he reminds readers of the human face of medicine.