The Library’s story began in 1880 with the founding of the Northport Literary and Social Union in the basement of the Presbyterian Church on Main Street. A library committee was in place by 1883 and during this year books were purchased, a librarian appointed, and a reading room opened in the Northport Journal building. In 1888 the union moved into a larger space in the Union Opera House on Union Place, incorporated, and renamed itself the Northport Literary and Library Union.
The union continued to work toward finding a permanent home and in 1914 purchased a lot on the corner of Main Street and Woodside Avenue with three thousand dollars raised through volunteer efforts in the community.
The Northport Public Library received its charter from the state in June 1914. Construction started on the new library building the following October. Harry E. Donnell, a well-known New York City architect, designed the tapestry brick building. Mr. Donnell was a member of the Delamater family, whose estate covered most of Eatons Neck at that time. Vail and Call, a local firm, was the builder. The library opened on December 13, 1915. In 1939 East Northport residents formed the Library Association of East Northport to establish a public library in the community.
The East Northport Public Library opened as a branch of the Northport Public Library in June 1940. A fire destroyed the library in 1945 but with help from the community, most of the books were saved. Damaged beyond repair, the school building was demolished and a new library building erected on the site in 1949. This building, expanded by a shelving area in 1966, served the community until the mid-1990s. In 1997 it was replaced at the same location by the present East Northport Public Library.
The Northport-East Northport Public Library celebrated its centennial in 2014.
Northport-East Northport Public Library is a member of the Long Island Library Resources Council.