As a young boy, Costello lived at the New York House of Refuge, a place for juveniles convicted of crimes or adjudicated as vagrants.
[1] He was one of a number of small boys given a place to live and work at the 800-acre (3.2 km2) Long Island Thoroughbred racehorse farm of George L. Lorillard.
There, Costello was given an education in a classroom built at the stables by Lorillard, who encouraged their studies and gave prizes to leading students.
Along with the other boys, Tom Costello helped maintain the stables and learned to ride horses.
In 1881 Tom Costello also rode Memento to victory in the inaugural running of the Spinaway Stakes at Saratoga Race Course; at Monmouth Park Racetrack in New Jersey, he won back-to-back editions of the Long Branch Handicap aboard Monitor.