The Urantia Book's origin story begins in Chicago around 1911, when the physician William S. Sadler and his wife Lena, also a physician, began observing a neighbor who spoke in his sleep in a manner Sadler could not medically explain. By the 1920s the case had grown into extensive automatic writing, and Sadler organized a discussion group, formalized in 1925 as the Forum, whose members submitted written questions that the sleeping subject's writings appeared to answer. A small Contact Commission of five people, including the Sadlers, managed the resulting manuscript over roughly two more decades. The individual through whom the material reportedly came, sometimes called the Conduit or the sleeping subject, was never publicly identified during his lifetime, and Sadler, who had made a career of investigating and debunking paranormal claims, wrote in his own 1929 book The Mind at Mischief that this was a case he found himself unable to classify.
The Urantia Foundation, a nonprofit Sadler helped establish in Chicago in 1950, published the completed manuscript as The Urantia Book on October 12, 1955: 2,097 pages divided into four parts and 196 numbered papers, presented as having been transmitted by celestial beings rather than composed by any human author. The book covers cosmology, the history of the universe and of life on a planet it calls Urantia, and an extended account of the life of Jesus.