The Aerial Phenomena Research Organization (APRO) was an American civilian group that collected and investigated reports of unidentified flying objects from 1952 until 1988. Coral Lorenzen and her husband, Jim, founded it in January 1952 in Sturgeon Bay, Wisconsin, as a central clearinghouse for sighting reports. The astronomer J. Allen Hynek later named APRO and NICAP as the two best civilian UFO groups of their time.

Before 1960 the Lorenzens lived in Alamogordo, New Mexico, where both worked at Holloman Air Force Base and built contacts among scientists and military personnel; in 1960 they moved APRO to Tucson, Arizona. The group ran a nationwide network of field investigators, issued the bimonthly APRO Bulletin and relied on consulting scientists with doctorates. Among them were the University of Arizona atmospheric physicist James E. McDonald and the Berkeley engineering professor James Harder, APRO's director of research from 1969 to 1982. Both were among six scientists who testified on UFOs before the House Committee on Science and Astronautics on July 29, 1968. In 1969 a sizable share of APRO's midwestern membership broke away to form the Midwest UFO Network, which grew into MUFON.

APRO was drawn into several of the most publicized cases of the 1970s. After the 1973 Pascagoula abduction report, Harder and Hynek interviewed the two shipyard workers under hypnosis and told reporters their accounts were likely based on fact. After the 1975 Travis Walton case, the National Enquirer reported that Walton and his co-workers had passed polygraph tests given by the paper and by APRO. The skeptic Robert Sheaffer later wrote that an earlier test the two had arranged, with the examiner John J. McCarthy, had found "gross deception"; Walton has maintained his account. Paul Bennewitz joined APRO in the 1970s; former Air Force Office of Special Investigations agent Richard Doty later said he had been tasked with feeding false information to UFO researchers, Bennewitz among them. Asked about reported CIA monitoring, the Lorenzens said the agency would be "derelict in their duty" if it did not watch them.

Jim Lorenzen passed away in 1986 and Coral in 1988, and APRO wound down by the end of 1988. Its case files spent about 35 years in storage before moving on November 25, 2023, to the National UFO Historical Records Center in New Mexico, the archive founded by David Marler. KJZZ reported that the collection filled 13 file cabinets and 50 boxes. The archive drew new attention in 2026, when the Pentagon's All-domain Anomaly Resolution Office moved to buy a subscription to the center's pre-1990 holdings. Allan Lavigne, who appears on podcasts as a former APRO investigator, also revived the name; Richard Dolan promoted a March 2026 interview in which Lavigne described what Dolan called a secret 1978 plan to tell the public about aliens.

APRO's emphasis on field investigation and credentialed consultants set it apart from the more political NICAP, and its former members went on to build MUFON. Its case files now sit in what Marler calls the largest assembled collection of historical UFO case files in U.S. history.