The Revolutionary Socialist Party, initially known as the International Socialist Labour Party, was a political party in Britain. Its origins were in the British Section of the International Socialist Labour Party, a De Leonist group, formed in 1912 following disputes within the Socialist Labour Party of Great Britain (SLP). It met under the name British Section of the International Socialist Labour Party between 1912 and 1937, standing municipal election candidates between 1919 and 1934 and general election candidates in 1918 and 1929, and Revolutionary Socialist Party between 1936 and 1941.