The Edinburgh-based Revolutionary Socialist Party was a Trotskyist group. It developed out of the British Section of the International Socialist Labour Party, a socialist grouping formed around the teachings of Daniel De Leon which split from the Socialist Labour Party during World War I. After rejecting several approaches from the SLP to rejoin, the small party moved towards Trotskyism as a result of their own study and became the RSP.
Revolutionary Socialist Party is a Marxist-Leninist political party in India. The party was founded on March 19 1940 and has its roots in the Bengali liberation movement Anushilan Samiti and the Hindustan Socialist Republican Army. The party got around 0,4% of the votes and three seats in the Lok Sabha elections 1999 and 2004.
Revolutionary Socialist Party (Bolshevik) [RSP(B)] was formed as a splinter-group from Revolutionary Socialist Party in Kerala in 2001. The party leader at the time of its formation was Baby John, formerly an important RSP leader in Kerala.