The Social Democratic Czechoslavonic party in Austria (Czech: Sociálně Demokratická strana Českoslovanská v Rakousku) was a political group founded on 7 April 1878 in Austria-Hungary as a regional wing of the Social Democratic Party of Austria.
Founded in Břevnov atop earlier social democratic initiatives, such as the Ouls, it represented much of the Kingdom of Bohemia in the Austrian parliament, and its significant role in the political life of the empire was one of the factors that led to the creation of an independent Czechoslovakia.
After the collapse of Austria-Hungary at the end of the First World War, the party became one of the leading parties of the first Czechoslovak Republic.
Its members were split over whether to join the Comintern, which in 1921 resulted in the fracturing of the party, with a large part of its membership then forming the new Communist Party of Czechoslovakia.

During the occupation of Czechoslovakia by Nazi Germany, the party was officially abolished, but its members organized resistance movements contrary to the laws of the German-controlled Protectorate of Bohemia and Moravia, both at home and abroad.
After the re-establishment of the Czechoslovak Republic in 1945, the party returned to its pre-war structure and became a member of the National Front which formed a new governing coalition.
In 1948, after the Communist Party of Czechoslovakia gained a parliamentary majority, the Czech Social Democratic Party was incorporated into the Communist Party.
At the time of the Prague Spring, a reformist movement 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 of 1989 that the party was recreated.
Since the dissolution of Czechoslovakia, which came into effect on 1 January 1993, the ČSSD has been one of the major political parties of the Czech Republic, and until October 2017 was always one of the two parties with the largest number of seats in the Chamber of Deputies.

At the 1998 parliamentary election, the party won the largest number of seats but failed to form a coalition government, so formed a minority government under its leader Miloš Zeman.
 With only 74 seats out of 200, the government had confidence and supply from the Civic Democratic Party (ODS), under the so-called Opposition Agreement.

At the elections of 2002, the party gained 70 of the 200 seats in the of Deputies of the Czech Republic Chamber of Deputies.
Its leader Vladimír Špidla became prime minister, heading a coalition with two small centre-right parties, the Christian and Democratic Union – Czechoslovak People's Party (KDU–ČSL) and the Freedom Union – Democratic Union (US-DEU) until he was forced to resign in 2004 after the ČSSD lost in the European Parliament elections of 2004
The next leader was Stanislav Gross, serving as leader from 26 June 2004 to 26 April 2005 and as prime minister from 4 August 2004 to 25 April 2005.
He resigned after a scandal when he was unable to explain the source of money used to buy his house.

The successor of Gross as prime minister was Jiří Paroubek, while Bohuslav Sobotka became acting party leader from 26 April 2005 to 13 May 2006.
Paroubek was then elected as the new party leader in the run-up to the June 2006 elections, at which the party won 32.3% of the vote and 74 out of 200 seats.
The election at first caused a stalemate, since the centre-right parties plus the Green Party and the centre-left parties each had exactly 100 seats.
The stalemate was broken when two ČSSD deputies, Miloš Melčák and Michal Pohanka, abstained during a vote of confidence, allowing a coalition of the Civic Democrats (ODS), the KDU-ČSL, and the Green Party to form a government.
Hence the ČSSD went into opposition.

At the 2010 legislative elections on 28 and 29 May, the ČSSD gained 22.08% of the vote but remained the largest party, with 56 seats.
Failing to form a governing coalition, it remained in opposition to a government coalition of the ODS, conservative TOP 09 and conservative-liberal
The Social Democratic Czechoslavonic party in Austria (Czech: Sociálně Demokratická strana Českoslovanská v Rakousku) was a political group founded on 7 April 1878 in Austria-Hungary as a regional wing of the Social Democratic Party of Austria. Founded in Břevnov atop earlier social democratic initiatives, such as the Ouls, it represented much of the Kingdom of Bohemia in the Austrian parliament, and its significant role in the political life of the empire was one of the factors that led to the creation of an independent Czechoslovakia. After the collapse of Austria-Hungary at the end of the First World War, the party became one of the leading parties of the first Czechoslovak Republic. Its members were split over whether to join the Comintern, which in 1921 resulted in the fracturing of the party, with a large part of its membership then forming the new Communist Party of Czechoslovakia.
During the occupation of Czechoslovakia by Nazi Germany, the party was officially abolished, but its members organized resistance movements contrary to the laws of the German-controlled Protectorate of Bohemia and Moravia, both at home and abroad. After the re-establishment of the Czechoslovak Republic in 1945, the party returned to its pre-war structure and became a member of the National Front which formed a new governing coalition. In 1948, after the Communist Party of Czechoslovakia gained a parliamentary majority, the Czech Social Democratic Party was incorporated into the Communist Party. At the time of the Prague Spring, a reformist movement 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 of 1989 that the party was recreated. Since the dissolution of Czechoslovakia, which came into effect on 1 January 1993, the ČSSD has been one of the major political parties of the Czech Republic, and until October 2017 was always one of the two parties with the largest number of seats in the Chamber of Deputies.
At the 1998 parliamentary election, the party won the largest number of seats but failed to form a coalition government, so formed a minority government under its leader Miloš Zeman.  With only 74 seats out of 200, the government had confidence and supply from the Civic Democratic Party (ODS), under the so-called Opposition Agreement.
At the elections of 2002, the party gained 70 of the 200 seats in the of Deputies of the Czech Republic Chamber of Deputies. Its leader Vladimír Špidla became prime minister, heading a coalition with two small centre-right parties, the Christian and Democratic Union – Czechoslovak People's Party (KDU–ČSL) and the Freedom Union – Democratic Union (US-DEU) until he was forced to resign in 2004 after the ČSSD lost in the European Parliament elections of 2004
The next leader was Stanislav Gross, serving as leader from 26 June 2004 to 26 April 2005 and as prime minister from 4 August 2004 to 25 April 2005. He resigned after a scandal when he was unable to explain the source of money used to buy his house.
The successor of Gross as prime minister was Jiří Paroubek, while Bohuslav Sobotka became acting party leader from 26 April 2005 to 13 May 2006. Paroubek was then elected as the new party leader in the run-up to the June 2006 elections, at which the party won 32.3% of the vote and 74 out of 200 seats. The election at first caused a stalemate, since the centre-right parties plus the Green Party and the centre-left parties each had exactly 100 seats. The stalemate was broken when two ČSSD deputies, Miloš Melčák and Michal Pohanka, abstained during a vote of confidence, allowing a coalition of the Civic Democrats (ODS), the KDU-ČSL, and the Green Party to form a government. Hence the ČSSD went into opposition.
At the 2010 legislative elections on 28 and 29 May, the ČSSD gained 22.08% of the vote but remained the largest party, with 56 seats. Failing to form a governing coalition, it remained in opposition to a government coalition of the ODS, conservative TOP 09 and conservative-liberal 
Czech Social Democratic Party