In January of 1934, Christopher Morley hosted a party to celebrate the birthday of fictional detective Sherlock Holmes and unintentionally started what would become the Baker Street Irregulars (BSI) - one of the most preeminent Sherlockian societies in the world. Interest in the society grew rapidly after its formation was announced in Morley's Saturday Review of Literature columns "The Bowling Green" and "Trade Winds." In an effort to include only the most knowledgeable Sherlockians in the organization, Morley published a Sherlock Holmes crossword puzzle created by his brother Frank and announced that anyone who solved the entire puzzle would obtain official BSI membership.

The first official meeting took place in June 1934, and it was soon decided that, whenever possible, annual dinner meetings would be held in January to honor Sherlock Holmes' birthday. Annual meetings included toasts, speeches, and papers on Sherlockian topics as well as the official investiture of distinguished members. As the BSI grew in size through the 1930s, members formed scion societies in numerous cities across the United States. Scions and other Sherlockian societies hold their own meetings and events and many publish newsletters.

In 1946, the BSI began publishing the Baker Street Journal (BSJ), the society's official publication. Additional society-sponsored publications include the BSI archival series, which details the history of the society, the Baker Street Irregulars manuscript series, which analyzes original Arthur Conan Doyle manuscripts, and a third series which offers an international perspective on Sherlockian topics.