The Watch Tower Bible and Tract Society of Pennsylvania is a non-stock, not-for-profit organization headquartered in the New York City, New York borough of Brooklyn. It is the main legal entity used worldwide by Jehovah's Witnesses to direct, administer and develop doctrines for the religion and is often referred to by members of the religion simply as "the Society". It is the parent organization of a number of Watch Tower subsidiaries, including the Watchtower Society of New York and International Bible Students Association. The number of voting shareholders of the corporation is limited to between 300 and 500 "mature, active and faithful" male Jehovah's Witnesses. About 5800 Jehovah's Witnesses provide voluntary unpaid labour, as members of a religious order, in three large Watch Tower Society facilities in New York; nearly 15,000 other members of the order work at the Watch Tower Society's other facilities worldwide.

The organization was formed in 1881 as Zion's Watch Tower Tract Society for the purpose of distributing religious tracts. The society was incorporated in Pittsburgh, Pennsylvania on December 15, 1884. In 1896, the society was renamed Watch Tower Bible and Tract Society. Following a leadership dispute in the Bible Student movement, the Watch Tower Society remained associated with the branch of the movement that became known as Jehovah's Witnesses. In 1955, the corporation was renamed Watch Tower Bible and Tract Society of Pennsylvania. In 1976, all activities of the Watch Tower Society were brought under the supervision of the Governing Body of Jehovah's Witnesses.

1. ^ ^{a b} Pennsylvania Department of State.
2. ^ Watch Tower Bible & Tract Society 1959, p. 49
3. ^ Jehovah's Witnesses—Proclaimers of God's Kingdom. p. 229. 
4. ^ ^{a b} "Jehovahs loses comp case: Church may be forced to pay millions", New York Daily News, January 6, 2006. Retrieved October 3, 2009.
5. ^ Yearbook, Watch Tower Bible & Tract Society, 2009.
6. ^ Yearbook, Watch Tower Bible and Tract Society, 2012, page 55.
7. ^ "Report for Fiscal Year", Watch Tower, December 1, 1896, page 301, Reprints page 2077 Retrieved 2010-03-30, "WATCH TOWER BIBLE AND TRACT SOCIETY. REPORT FOR FISCAL YEAR ENDING DEC. 1, 1896. ALTHOUGH the above has been the recognized name of our Society for some four years, it was not until this year that the Board of Directors took the proper steps to have the name legally changed from ZION'S WATCH TOWER TRACT SOCIETY to that above. The new name seems to be in every way preferable."
8. ^ "Development of the Organization Structure", Jehovah's Witnesses – Proclaimers of God's Kingdom, 1993 Watch Tower, page 229, "Zion’s Watch Tower Tract Society. First formed in 1881 and then legally incorporated in the state of Pennsylvania on December 15, 1884. In 1896, its name was changed to Watch Tower Bible and Tract Society. Since 1955 it has been known as Watch Tower Bible and Tract Society of Pennsylvania."
9. ^ Franz 2007, pp. 80–107