The Farnsworth Art Museum traces its beginnings to Rockland resident Lucy Copeland Farnsworth, whose will stipulated that her estate was to be used to create “a library for the use of the public,” to preserve “as a public edifice the homestead of the late William A. Farnsworth on Elm Street, together with its contents,” and that a building she owned on Main Street “be put in condition to serve as an art gallery.”  
The Farnsworth’s non-circulating collection of books and periodicals relating to the history of art is one of the most comprehensive in the Rockland area. The scope of the library reflects the museum's permanent collection, with particularly strong holdings in American art—including painting, sculpture, Maine history, architecture and the decorative arts.

The comfortable reading room of the Farnsworth Library is enhanced by one of a pair of marble mantels imported for the U.S. Capitol and placed in the early robing room of the Supreme Court. The mantel eventually found its way to the Farnsworth Library after lying for some years in the Crypt of the Capitol amongst piles of old lumber, and after having been installed for a time in the 10,000-volume library on the second floor of the Washington, DC home of Justice Gray. Currently, the library holdings are being documented in preparation for a future online catalogue linked statewide to other institutions.
For those wishing to access only the museum's library, a library pass may be obtained at the main museum lobby and there is no admission fee.