Greenlawn is a hamlet and census-designated place (CDP) in Suffolk County, New York, United States. Located on Long Island in the Town of Huntington, the population was 13,742 at the 2010 census. Students primarily attend the Harborfields Central School District.
Originally known as Old Fields, it became known by the name Greenlawn with the coming of the Long Island Rail Road in 1870 or 1871. The LIRR chose the name Greenlawn for its station, apparently to project an idyllic rural/suburban image and foster resort travel to the beaches in Centerport. Greenlawn was well known for itspickle production during the 19th century as well as, to a lesser degree, potato and cabbage farms; the principal commodity, pickles, is still celebrated by the annual Pickle Festival, held by the local Greenlawn-Centerport Historical Association at the John Gardiner Farm.