Hell's Angels: The Strange and Terrible Saga of the Outlaw Motorcycle Gangs began as the article "The Motorcycle Gangs: Losers and Outsiders" for the May 17, 1965 issue of The Nation.
In March 1965, The Nation editor Carey McWilliams wrote to Hunter S. Thompson and offered to pay the journalist for an article on the subject of motorcycle gangs, and the Hells Angels in particular. Thompson took the job and the article, published about a month later, prompted book offers from several publishers interested in the topic.
Thompson spent the next year preparing for the new book in close quarters with the Hells Angels, in particular the San Francisco and Oakland chapters of the club and their president Ralph "Sonny" Barger. Thompson was straight-up with the Angels about his role as a journalist, knowing their distrust of reporters for what the club considered to be bad press. Thompson was introduced to the club by Birney Jarvis, a former patch-holder and then police-beat reporter for the San Francisco Chronicle. This introduction, coming from an Angel and reporter, allowed Thompson to get close to the gang in a way others had not been able.
Far from being wary of this outsider, the Angels were sincere in their participation, often talking at length over smokes, shots and beer into Thompson's tape recorder and reviewing early drafts of the article to ensure he had his facts straight. During his writings the Angels often visited his apartment at 318 Parnassus Avenue in San Francisco, much to the dismay of his wife, landlord and neighbors. Thompson, however, felt comfortable with the arrangement, so comfortable that when he was "jokingly" threatened with violence, he allegedly pointed to a loaded double-barrelled shotgun that he kept hanging on his wall and replied in a similar vein that he would "croak two of them first."