Family and education
Woolsey was born on January 3, 1877, in Aiken, South Carolina, to William Walton Woolsey and Katherine Buckingham Convers Woolsey. Woolsey was a descendant of George (Joris) Woolsey, one of the earliest settlers of New Amsterdam, and Thomas Cornell (settler). One member of his family graduated from Yale University in 1709; his granduncle Theodore Dwight Woolsey was president of that university from 1846 to 1872; and cousin Theodore Salisbury Woolsey was a professor of international law there. His half-sister, Gamel Woolsey, was a noted poet and novelist.
John Woolsey attended private school in Englewood, New Jersey and Phillips Academy. He went on to Yale and received an Artium Baccalaureus degree there in 1898. He got his Bachelor of Laws in 1901 from Columbia Law School, where he was a founder of the Columbia Law Review. He was in private practice in New York City, New York from 1901 to 1929.