The Lancaster Mennonite Historical Society serves as the official depository for records of the Atlantic Coast and Lancaster Conferences of the Mennonite Church. It also contains many records and publications of other organizations affiliated with those two conferences.

The Society's manuscript collections contain mostly unpublished hand- or type-written material. They can include the following materials and formats:

• Art Prints/Lithographs/Posters
• Audio Recordings
• Broadsides (or Handbills)
• Cemetery Records
• Correspondence
• Charts
• Deeds
• Diaries
• Ephemera
• Folk Art (e.g., Fraktur or Scherenschnitte)
• Genealogical Records
• Maps
• Newspaper Clippings (Obituaries, etc.)
• Photographs and Slides
• Postcards
• Sunday School Cards
• Video Recordings
• Wills