The contents consists of administrative records relating to committee meetings, society correspondence, legal records, financial records, membership subscriptions, society projects, events, newsletters and programmes. Records relating to the establishment of Castletown Heritage are also included.
Other material relates to Castletown Heritage's actions in preserving Castletown, its buildings and the surrounding area. Further records include the society's activities in collecting and preserving the memories of Castletown such as, the history of the town, memories of individuals, biographical information on individuals and the history of Castletown buildings and streets.
Further historical items include maritime related records, archaeological related material and various topics relating to social history, visits to the Island and the Castletown Gazette .