William Floyd was born on December 17, 1734, at his family’s Mastic estate in Brookhaven on the south shore of Long Island. He was the eldest son of Nicoll Floyd and Tabitha Smith Floyd and descended from English and Welsh settlers who had acquired extensive property in colonial New York. The estate encompassed thousands of acres, with fields, livestock, woodland, shoreline, and access to coastal shipping. Its prosperity depended upon the labor of tenants, servants, family members, and enslaved people.

Floyd received a modest local education rather than attending college. Later accounts emphasize that he was not a highly trained scholar, but he developed strong ability in farming and accounts. His practical education included managing crops, cattle, sheep, pigs, orchards, labor, buildings, credit, and the shipment of produce from the estate’s own landing. He also grew up within a broad network of Suffolk County families whose marriages linked landholding and political influence.

Both of Floyd’s parents died in 1755, only months apart, when William was twenty. As eldest son, he inherited responsibility for the estate and for younger siblings. The sudden transition demanded managerial competence and fixed his identity as a substantial farmer and landowner. Several siblings also formed influential connections: Ruth married Nathaniel Woodhull, while Charity married Ezra L’Hommedieu, both later active in Revolutionary politics.

In 1760 Floyd married Hannah Jones of Southampton. They established their family at Mastic and eventually had three children. Property, marriage, and militia participation integrated Floyd more deeply into county leadership. Like other large New York landowners, he held enslaved people, an institution that remained part of his household throughout his life.

By the early 1770s Floyd was respected less for oratory or formal learning than for independence, sound management, and local standing. He entered Suffolk County militia and public affairs as relations with Britain deteriorated. His selection in 1774 as a New York delegate to the Continental Congress marked the end of his early life as a largely local estate manager and began the national political service that made him a signer of the Declaration of Independence.