Donald Jeanne Ritchie (1920- ) is a mathematician and physicist who has been active in missile guidance system design and development and in arms control and disarmament studies. He began work as a production engineer at Bell Aircraft Corp (1940-42) before joining the Design Branch of Wright Air Development Center, Wright Field, OH (1942-45), where he participated in preliminary design work on jet aircraft. Following World War II, he attended Wayne University, completing degrees in Mathematics and Physics (BS, 1949) and Applied Mathematics (MS, 1951). He spent most of the next two decades at Bendix's Research Laboratory Division (Senior Mathematician, 1949-54; Project Engineer, 1955-57; Supervisory Mathematician, 1958-65; Assistant Department Head, Surveillance, Navigation, and Guidance, 1965-67) working on missile systems. He spent several brief periods outside Bendix, at Atomic Power Development Associates (Senior Mathematician, 1954-55), Crosley Division, Avco Manufacturing Co (Supervisor, Missile Systems, 1957), and Corvy Division, Melpar Inc, Scientific Analysis Office (Branch Leader, 1957-58). He then joined the faculty of Embry-Riddle Aeronautical Institute (now Embry-Riddle Aeronautical University) as Professor of Aeronautical Engineering, Director of Research, and Chairman of the Aeronautical Engineering Division (1967-?). During this time he also worked as a consultant to the United States Air Force Foreign Technical Intelligence Division and the Smithsonian Institution's National Air and Space Museum.