Collection consists of administrative records, correspondence, manuscripts and typescripts, printed ephemera, and audio recordings documenting the history of the Speckled Band, the Boston branch of the Baker Street Irregulars. Administrative scrapbooks include communications and memoranda, meeting agendas and minutes, and event ephemera, such as invitations and programs. Notable correspondents include Max Beerbohm, Adrian Conan Doyle, Christopher Morley, Edgar W. Smith, Rex Stout, and many more. In some cases, files contain copies of original materials; these are identified in the file titles.

The audio recordings include music composed by club member James Montgomery, as well as recordings of members and meetings of Sherlock Holmes societies. Topics encompass the activities and internal operations of Sherlockian societies, the personal lives and interests of their members, and related pursuits, including materials concerning crime novelist Dorothy L. Sayers and stage actor William Gillette.