The not-for-profit Middlesex County Historical Society is dedicated to preserving the history of Middlesex County and providing programs for adults and children to increase their understanding of the past. Museum exhibits, historic graveyard walking tours, Civil War re-enactments and a lecture series are among its many annual events.
Since 1959, the society has been housed in a Federal brick mansion that is the former home of General Joseph K.F. Mansfield, a Civil War hero who died at the battle of Antietam in 1862.
Exhibits at the Mansfield House have showcased artifacts from the society's permanent collection as well as 19th century women's clothing, immigrant groups, the rise and fall of manufacturing in Middlesex County, and death and dying from colonial times to the present. A permanent exhibit, Hard & Stirring Times: Middletown and the Civil War, explores local soldiers' experiences through photographs, military gear, diaries and letters home.
Grounds at the Mansfield House also feature a colorful herb garden maintained by the Middletown Garden Club. The garden is open daily. It also has a gift shop. The historical society is governed by a 15-member board of directors.