The Social Democratic Czechoslavonic party in Austria (Czech: Sociálně Demokratická strana Českoslovanská v Rakousku) was founded on 7 April 1878 in Austria-Hungary representing the Kingdom of Bohemia in the Austrian parliament. Its role in the political life of the empire was one of the factors that lead to the creation of independent Czechoslovak Republic. After the collapse of Austria-Hungary, the party became one of the leading parties of the first Czechoslovak Republic.
During the occupation of Czechoslovakia by Nazi Germany, the party was officially abolished, but its members organised resistance movements illegally within the Protectorate of Bohemia and Moravia and abroad. After the re-establishment of the Czechoslovak Republic in 1945, the party returned to its pre-existing structure and became a member of the National Front. In 1948, after the Communist Party assumed the parliamentary majority, the Czech Social Democratic Party was abolished along with all other non-communist parties. Under the reformist environment in 1968, there were talks about allowing the recreation of a Social Democratic party, but Soviet intervention put an end to such ideas. It was only after the Velvet Revolution in 1989, when the party was recreated. Since the dissolution of Czechoslovakia, ČSSD has been one of the major political parties in the Czech Republic.
The current chairman of the party is Jiří Paroubek since 2006. His predecessor was Stanislav Gross from 26 June 2004 to 26 April 2005. Gross resigned after a scandal which arose due to his inability to explain the source of financial resources used to pay for his home. Gross's predecessor Vladimír Špidla was forced to resign in 2004 after the ČSSD lost in the 2004 European Parliamentary elections.
Following the 2010 legislative elections, the ČSSD gained 22.08% of the vote and became the largest party with 56 seats, but having failed to form a governing coalition, remained in opposition to a coalition of the ODS, conservative TOP 09 and conservative-liberal Public Affairs parties.