The Baker Street Irregulars

The oldest Sherlock Holmes society is the Baker Street Irregulars, founded in 1934 by Christopher Morley. Membership—in contrast to the custom for practically all other Sherlockian societies—is by invitation only. The major event is an annual January dinner in New York, the centrepiece of the annual "birthday weekend" that brings hundreds of Sherlockians to New York.

The BSI has dozens of "scion societies" across the United States, and kindred societies in other countries. It publishes the quarterly Baker Street Journal.

• Al Gregory's list of Irregulars, arranged by Investiture (on Sherlockian.Net)
• The Baker Street Irregulars Trust
• Finding aid for archives at Harvard University
• BSI Archival History and Blog
• Canadian Baker Street Irregulars
• Lyndsay Faye explains the BSI's January weekend and explains why the BSI is not a fandom
• A band that shares nothing except the name
• The Junior Sherlockian Society 

United States

Central

• The Hounds of the Baskerville [sic] (Chicago)
• The Norwegian Explorers (Minnesota)
• The Afghanistan Perceivers (Tulsa, Oklahoma)
• Criterion Bar Association, Chicago
• Illustrious Clients of Indianapolis
• Nashville Scholars
• The Giant Rats of Sumatra (Memphis, Tennessee)
• The Younger Stamfords (Iowa City)
• The Crew of the Barque Lone Star (Dallas, Fort Worth)
• Diogenes Club of Dallas
• The Hansoms of John Clayton, Peoria
• The Hated Rivals on the Surrey Shore (Indianapolis)
• Maiwand Jezails (Omaha)
• McMurdo's Camp (Michigan)
• The Original Tree Worshippers of Rock County (Wisconsin)
• John Openshaw Society, Houston
• The Agra Treasurers (Dayton, Ohio)
• Parallel Case of St. Louis
• Occupants of the Empty House (southern Illinois)
• The Notorious Canary-Trainers (Madison, Wisconsin)

East

• Three Garridebs of Westchester County
• The Red Circle of Washington
• Amateur Mendicant Society of Detroit
• Watson's Tin Box (Maryland)
• A Scintillation of Scions
• The Baker Street Breakfast Club, Vermont
• Mrs. Hudson's Cliffdwellers, New Jersey
• Sherlock Holmes Pipe Club of Boston
• White Rose Irregulars (York, Pennsylvania)
• Society of the Naval Treaty (Annapolis)
• The Pleasant Places of Florida
• Priory Scholars of New York
• The Hansom Wheels, Columbia, South Carolina
• Sherlock Holmes Meetups
• The Avenging Winters of Albany
• Mrs. Hudson's Lodgers
• Sherlock Holmes Club

West

• The Blustering Gales from the South-West
• The Noble and Most Singular Order of the Blue Carbuncle, Portland, Oregon
• The Sound of the Baskervilles (Washington state)
• Curious Collectors of Baker Street (Los Angeles)
• The Sherlock Breakfast Club (Los Angeles)
• Dr. Watson's Neglected Patients (Denver)