Student Art Students’ League, New York City, 1900-1903, Ecole des Beaux Arts, Paris, 1904-1906, American Academy in Rome, 1912-1915. Pupil of George Grey Barnard and Anton Mercie.
When he was about 12 years old his family immigrated to the United States where he began his sculptural studies at the Art Students League in New York City. He continued these at both the École des Beaux-Arts in Paris and at the American Academy in Rome. He became a United States citizen in 1912 and during the First World War served in the camouflage section of the United States. Navy.
In 1927 he was elected into the National Academy of Design as an Associate member and became a full Academician in 1934.
In 1932 Gregory produced 9 marble bas reliefs for Paul Cret"s Folger Shakespeare Library in Washington, District of Columbia Each panel depicted a scene from a different play by Shakespeare. In 1937, he completed a gilded bronze equestrian statue of Anthony Wayne for the Philadelphia Museum of Artist
Gregory is well known for his architectural sculpture. Examples include bas relief panels on the structure and sarcophagus of the Huntington Mausoleum by architect John Russell Pope at The Huntington Library in San Marino, California.
And the larger-than-life panels, Columbia and Urban, on either side of the steps in John Marshall Park, Judiciary Square, Washington, District of Columbia
Served as assistant inspector, naval construction camouflage Navy Department, 1918. Principal works include: Panels on Folger Shakespeare Library, Washington. Member National Sculpture Society (president 1934-1939, honorary president since 1953), National Academy Design, National Institute Arts and Letters.
Member Beaux Arts Institute Design (New York City), American International Assurance.
Member Art communications of New York City, since 1957.
Married Katharine Van Rensselaer Crosby, June 7, 1922.