The Clapham Sect or Clapham Saints were a group of Church of England social reformers based in Clapham, London at the beginning of the 19th century (active 1780s–1840s). John Newton (1725-1807) was the founder. They are described by the historian Stephen Michael Tomkins as "a network of friends and families in England, with William Wilberforce as its centre of gravity, who were powerfully bound together by their shared moral and spiritual values, by their religious mission and social activism, by their love for each other, and by marriage". By 1848 when an evangelical John Bird Sumner became Archbishop of Canterbury, between the fourth and third of all Anglican clergy were linked to the movement, which by then had diversified greatly in its goals and they were no longer considered an organized faction.
Its members were chiefly prominent and wealthy evangelical Anglicans who shared common political goals concerning the liberation of slaves, the abolition of the slave trade and the reform of the penal system.
The group's name originates from those attending Holy Trinity Church on Clapham Common, an area south-west of London then surrounded by fashionable villas. Henry Venn was curate at Holy Trinity (1754) and his son John became rector (1792-1813). Wilberforce and Thornton, two of the group's most influential leaders, resided nearby and many of the meetings were held in their houses. They were supported by Beilby Porteus, Bishop of London, who sympathised with many of their aims. The term "Clapham Sect" was a later invention by James Stephen in an article of 1844 which celebrated and romanticised the work of these reformers. In their own time the group used no particular name, but they were lampooned by outsiders as "the saints".