The Bulgarian Socialist Party (Bulgarian: Bălgarska Socialističeska Partija or Българска социалистическа партия) (BSP or БСП) is a political party in Bulgaria and successor to the Bulgarian Communist Party. It was formed in 1990 in post-communist Bulgaria, following the decision of the Bulgarian Communist Party to abandon Marxism-Leninism. The BSP is a member of the Socialist International and is led by Sergei Stanishev.
In the 2001 parliamentary elections it was part of the Coalition for Bulgaria alliance which picked up 48 of 240 seats in the National Assembly (Narodno Sabranie), having attracted 17.1% of the popular vote. The current Bulgarian president, Georgi Parvanov, was a member and chairman of the party. At the last legislative elections, held on 25 June 2005, the Coalition won 33.98% of the popular vote and 82 out of 240 seats.