The Clapham Sect was an influential group of like-minded social reformers in England at the beginning of the nineteenth century (active c. 1790 - 1830).

Its members were chiefly prominent and wealthy evangelical Anglicans who shared common political views concerning the liberation of slaves, the abolition of the slave trade and the reform of the penal system.

The group's name originates from the village of Clapham, south of London, where both Wilberforce and Thornton, the sect's two most influential leaders, resided and where many of the group's meetings were held. They were supported by Beilby Porteus, Bishop of London, who sympathised with many of their aims.

After many decades of work both in Parliament and in general society, they and their successors saw their efforts rewarded, as England finally banned the slave trade, both in the British Isles and the Empire, and used its influence and power to eradicate legal slavery throughout the world.

Lampooned in their day as "the saints", the group published a journal, the Christian Observer, and were also credited with the foundation of several missionary and tract societies, including the British and Foreign Bible Society and the Church Missionary Society.

Members of The Clapham Sect included:

Thomas Gisbourne (1758 - 1846), clergyman and author
Charles Grant (1746 - 1823), business administrator
Zachary Macaulay (1768 - 1838), estate manager, colonial governor, father of Thomas Macaulay
Hannah More (1745 - 1835), writer and philanthropist
Granville Sharp (1735 - 1813), scholar and administrator
Charles Simeon (1759 - 1836), Anglican minister, promoter of missions
William Smith, M.P. (1756 - 1835), parliamentarian
James Stephen (1758 - 1832), Master of Chancery
Lord Teignmouth (1751 - 1834), Governor-General of India
Henry Thornton (1760 - 1815), economist, banker, philanthropist, MP for Southwark
Henry Venn (1725 - 1797), founder of the group
John Venn (1759 - 1813), Rector of Holy Trinity Church, Clapham
William Wilberforce (1759 - 1833), parliamentarian, leading abolitionist