- Mary Jobe Akeley and Peace Sanctuary Collection
- Nathan Belcher correspondence
- Cephas Brainerd papers
- Anna Hempstead Branch collection
- Prudence Crandall papers
- Daboll Family papers and memorabilia
- Elsie DeWitt Family Papers
- Timothy Green collection
- Richard and Beatrice Mansfield letters and memorabilia
- New London Postcard collection
- New London Development Corporation papers
- Union Station renovation papers
- Louis Sheaffer Collection of Eugene O'Neill
- John Bishop and 29th Connecticut Volunteers Collection
- Thomas Pimer Collection
- Mccracken Civil War Correspondence
- Cornelius B. Gold papers
- William Ingram collection