The Clapham Sect, or Clapham Saints, were a group of social reformers associated with Holy Trinity Clapham in the period from the 1780s to the 1840s. Despite the label "sect", most members remained in the established Church of England, which was highly interwoven with offices of state. However, its successors were in many cases outside of the established Anglican Church.

Clapham is a district in south west London, England, lying mostly within the London Borough of Lambeth, but with some areas extending into the neighbouring London Borough of Wandsworth.