Stringfield was director of Civilian Research, Interplanetary Flying Objects (CRIFO), and published a monthly newsletter, ORBIT. In 1957 he became public relations adviser for the civilian UFO group NICAP under the direction of Donald Keyhoe, a friend of his since 1953. From 1967-1969, Stringfield served as an "Early Warning Coordinator" for the Condon Committee. During the 1970s, he wrote a number of books about alleged recoveries of alien spaceships and alien bodies.
In 1978, Stringfield served as UFO research adviser to Grenada Prime Minister Sir Eric Gairy. Privately, Stringfield worked as Director of Public Relations and Marketing Services for DuBois Chemicals, a division of Chemed Corporation, Cincinnati. He self-published "Status Reports" on alleged UFO "crash-retrievals" until his death. He died December 18, 1994 after a long battle with lung cancer.
Retrievals of the Third Kind: A case study of alleged UFOs and occupants in military custody (1978), presented as a speaker at the Ninth Annual MUFON Symposium in Dayton, Ohio, July, 1978. (Unofficially: Status Report I)
The UFO Crash/Retrieval Syndrome: Status report II: New Sources, New Data (1980)
UFO Crash/Retrievals: Amassing the Evidence: Status Report III (1982)
The fatal encounter at Ft. Dix-McGuire: A case study: Status Report IV (1985)
UFO Crash/Retrievals: Is the coverup lid lifting?: Status Report V (1989)
UFO Crash/Retrievals: The Inner sanctum : Status Report VI (1991)
UFO Crash/Retrievals: Search for Proof in a Hall of Mirrors: Status Report VII (1994)