Before joining the Association staff, Dr. Caldwell was a St. Louis physician, a public health official in charge of hospitals in Panama during the building of the canal, a member of the Rockefeller Foundation's Yellow Fever Commission in Mexico and superintendent of State University of Iowa Hospital and of Tampa (Florida) Municipal Hospital. At AHA, he took the leadership in organizing state hospital associations, the American College of Hospital Administrators and the first course in hospital administration, located at the University of Chicago.