Incorporated in 1938, the Portsmouth Historical Society is a non-profit volunteer educational organization devoted to the preservation of Portsmouth's historic buildings, sites and artifacts.
The society worked to restore the Christian Union Church, which is the society's current headquarters and musuem. The society has also preseved the Southermost School (1725), which is listed on the National Register of Historic Places, and the Old Town Hall (1850).
The society's board meets the third Monday of each month at 7 p.m. at the Portsmouth Historical Society Museum.