The Watch Tower Bible and Tract Society of Pennsylvania is the main legal body used around the world by Jehovah's Witnesses to organize the religion and also to decide on its official list of beliefs. Members of Jehovah's Witnesses usually call it just as "the Society". Its headquarters are in Brooklyn, New York in the United States and its rules allow only between 300 and 500 members. All of them must be "mature, active and faithful" male Jehovah's Witnesses.
A preacher, Charles Taze Russell, started the organization in 1881 as Zion's Watch Tower Tract Society, so he could share religious pamphlets with people. In 1896, its name was changed to Watch Tower Bible and Tract Society. When Russell died in 1916, a fight started between some of the society's directors and the man who took his place, Joseph Franklin Rutherford. The fight became very bitter and many of the people who had followed Russell, who were called International Bible Students, left and started other religious groups. But Rutherford stayed as president of the society and in 1931 the Bible Student groups around the world changed their name to Jehovah's witnesses. In 1955, the corporation changed its name again to Watch Tower Bible and Tract Society of Pennsylvania. From 1976, the Governing Body of Jehovah's Witnesses began to control all the decisions and the work of the Watch Tower Society.