Revolutionary Socialist Party (RSP) is a Marxist–Leninist political party in India. The party was founded on 19 March 1940 and has its roots in the Bengal liberation movement Anushilan Samitiand the Hindustan Socialist Republican Army. The party got around 0.4% of the votes and three seats in the Lok Sabhaelections in 1999 and 2004. It is part of the state government in Tripura. RSP has always had its stronghold in West Bengal, but has branches in a total of 18 states.
In Kerala, it is concentrated in the Kollam area, with support amongst fishing communities. Its Kerala branch originates from a split in the Kerala Socialist Party.K. Pankaj akshan, general secretary until 2008, was a KSP member. The party has 7 seats in the West Bengalstate assembly, and 2 each in Keral and Tripura. RSP is part of the Left Front in West Bengal and Tripura. In Kerala the party is part of UDF now.