From their humble origins as small, loose-knit groups of Bible students in Pennsylvania in the 1870s, Charles Taze Russell and his followers laid the foundations of a highly visible, and frequently controversial, worldwide religious organisation known since 1931 as the Jehovah's Witnesses. Despite the Witnesses' broad historical role in defining and shaping understandings of religious tolerance, freedom of conscience, and civil liberties around the world, historians have paid very little attention to the Witnesses, with the notable exception of their treatment in Nazi Germany and the United States and Canada in wartime. The paucity of historical knowledge is all the more surprising given their visibility and notoriety. This article aims to initiate discussion of this under-researched history by addressing what has been written, by whom, and for what purpose. It represents the first effort to evaluate the English-language historical literature on the Jehovah's Witnesses and the Watch Tower Bible and Tract Society.