in Boston, Massachusetts, U.S., independent research library containing about 750,000 volumes and housing an art gallery featuring the works of Boston-area artists and artisans. The library was founded in 1807. It moved into its present building on Beacon Street in the late 1840s and was expanded several times. Special collections include Confederate state imprints, the King's Chapel collection (1698), and a large collection of historical prints and photographs.

Its conservation department was one of the first established in the United States. The art gallery, founded in 1827, features 18th- and 19th-century Boston and New England prints.