The Historical Room of the Guilford Free Library holds materials documenting Guilford's history and genealogy, past and present. This includes books, diaries, letters, maps, photographs, scrapbooks, high school yearbooks, and early tax lists. Also included are microfilm reels of the Federal census for New Haven and Middlesex counties from 1800 to 1920, and the Shore Line Times newspaper from 1877 to date.

Visitor information is available in the foyer of the library's west entrance, off of Park Street.