According to architectural historian Richard Candee, the Belknap Mill is one of the nation's most important mills. Built between 1823 and 1828 to manufacture wool and cotton cloth, it had the latest technology of its time. The bell in its tower was cast by George Holbrook, an apprentice to Paul Revere. In 1861, during the Civil War, the Belknap Mill was one of the first mills in the country to convert from weaving to knitting. In 1918, owner J. P. Morin added a hydroelectric power plant, and the Belknap Mill operated as a hosiery mill until 1969.
After the City of Laconia adopted an Urban Renewal plan to improve downtown, many surrounding mill buildings were demolished. In response, the Save the Mill Society convened on February 4, 1970, to adopt bylaws, elect officers, and appoint committees. By January 1974, the Society became the owner of the Belknap-Sulloway Mill and changed its name to The Belknap Mill Society in 1976. This organization was the first to receive federal funds and an award from the National Trust for preserving an industrial structure, with its efforts being covered in LIFE and Yankee magazines and the comic strip Archie.
Today, the Belknap Mill is the only remaining mill representing the early form of industrialization in New England, as similar mills have either been updated or destroyed. The Belknap Mill Society has transformed the mill into a cultural center and has won national and state awards for its leadership in educational programs, exhibits, preservation, and community service.