Founded in 1901 as the Site and Relic Society, the Germantown Historical Society is an educational and research center dedicated to preserving and interpreting the history of the original German Township in northwest Philadelphia, including the contemporary neighborhoods of Germantown, Mt. Airy, and Chestnut Hill and the Wissahickon Valley. The Society houses a collection of artifacts, books, manuscripts, maps, and images documenting Germantown's many stories.

The archival collections of the Germantown Historical Society total over 625 linear feet of materials dating from 1688 to the present. Holdings include personal papers, manuscripts, business records and institutional archives as well as books, newspapers, church and cemetery records, maps, deeds and other land records, scrapbooks and oral history interviews. The image collection is especially rich and includes thousands of glass plate negatives, daguerreotypes and lantern slides, and well over 5,000 photographs depicting residents, streets and structures from the mid-19th century to the present. Collections of particular note include the archives of the African-American Genealogy Group, the Germantown Theatre Guild, Germantown Hospital and the Philadelphia, Germantown and Norristown Rail Road.