Establishment Initial discussions about forming a
Marxist political party in
Lithuania began early in 1895, with a number of informal gatherings bringing together social democrats of various stripes resulting in a preparatory conference in the summer of that year. Differences in objectives became clear between ethnic
Jews and ethnic
Lithuanians and
Poles, with the former seeing themselves essentially as Russian Marxists while the latter two groups harboured both revolutionary and national aspirations. Moreover, the ethnic Poles and Lithuanians saw themselves divided over the question of alliance with non-Marxist liberals. As a result, not one but three Marxist political organisations would emerge in Lithuania between 1895 and 1897. The Social Democratic Party of Lithuania (LSDP) was founded on 1 May (19 April O.S.) 1896 at a secret congress held in an apartment in
Vilnius. Among the 13 delegates were
Andrius Domaševičius and
Alfonsas Moravskis—a pair of intellectuals regarded as the central organisers of the new political entity—and the future President of Lithuania,
Kazys Grinius, as well as a number of worker activists. Also in attendance as a representative of the radical youth movement was an 18-year-old ethnic Pole named
Felix Dzerzhinsky, later the head of the
Soviet secret police. Newspapers were published abroad, printed in
East Prussia (or sometimes
Switzerland or
France) and smuggled across the border. Technical assistance was occasionally provided by the
Social Democracy of the Kingdom of Poland and Lithuania party, headed by
Julian Marchlewski. The party's first program, approved in 1896, was directly influenced by the
Erfurt Program, as well as the resolutions of the
Second International and the program of the
Social Democracy of the Kingdom of Poland and the
Polish Socialist Party. It called for an independent democratic republic of Lithuania in a federation with
Poland,
Latvia,
Belarus and
Ukraine. It was the first political organization in Lithuania to call for Lithuania's independence from the
Russian Empire. This smuggling of Lithuanian newspapers had historical antecedents. Following the
Polish and Lithuanian Uprising of 1863, the Tsarist regime had banned publication of all newspapers which used the
Latin alphabet, a measure which amounted to a
de facto ban of the entire Lithuanian press. This proscription extended for the rest of the 19th Century; in 1898 of 18 newspapers appearing in Lithuanian, 11 were published by Lithuanians in emigration in America and the other 7 were published in East Prussia. It was the first Lithuanian political party and one of the major parties who initiated the assembly called
Great Seimas of Vilnius in 1905. In the Great Seimas, it represented the most radical left wing of the assembly and had poor relations with the assembly's other representatives, which belonged to the liberal
Lithuanian Democratic Party and the Lithuanian
Christian democratic current. These two parties opposed LSDP's program of armed struggle against the Russian government and it was thus not adopted by the assembly.
Split and reformation During the
German occupation of Lithuania from 1915 to 1918, the party abandoned previous projects for a multinational federation or autonomy within Russia, began to call for an independent democratic Lithuania and joined the
Council of Lithuania. However, it experienced an internal crisis in late 1918 and was divided between supporting the
Constituent Assembly of Lithuania or
soviet rule. In December 1918, the majority of LSDP members in
Vilnius, led by
Andrius Domaševičius, left the party and established the short-lived
LSDP-LKP which recognized the
Bolshevik-supported revolutionary government led by
Vincas Mickevičius-Kapsukas. A minority group of social democrats led by Steponas Kairys and
Juozas Paknys remained in Lithuania, supported the government of
Mykolas Sleževičius during the
Lithuanian Wars of Independence and reestablished the party ahead of the
1920 Lithuanian parliamentary election. The party was one of the major political powers during the Lithuanian independence period between 1918 and 1940. Following the election of 1926, the party formed a left-wing coalition government with Lithuanian Peasant Popular Union. This government was dismissed after the
1926 Lithuanian coup d'état. The authoritarian regime of
Antanas Smetona banned all political parties in 1936.
Period of Soviet occupation During the
Soviet occupation era, no democratically constituted political parties existed within Lithuania. Therefore, between 1945 and the 1989 restoration of independence, the party was assembled and worked covertly in exile.
1989–2001 In 1989, the Social Democratic Party of Lithuania was restored.
Kazimieras Antanavičius was elected to be party's leader. The party had 9 seats in the
Supreme Council – Reconstituent Seimas and was not successful in substantially increasing the number in the following elections, with 8 seats won in
1992 and 12 in
1996. In 1999, the party's congress elected a new leader,
Vytenis Andriukaitis and merger negotiations with the
Democratic Labour Party of Lithuania (LDDP)–the bulk of the former
Communist Party of Lithuania (which had broken away from Moscow in 1989) began. Members of the party opposing the merger left to establish "Social democracy 2000" (later renamed "
Social Democratic Union of Lithuania"). The SDPL-LDDP coalition won 51 of the 141 seats in the
elections in 2000 (with 19 going to the Social Democrats). However, despite success in the elections, the coalition parties had to settle for a place in the opposition until 2001, when the collapse of the
ruling coalition between Liberals and New Union allowed ex-President
Algirdas Brazauskas to form a government with New Union.
Since 2001 In 2001, the Social Democratic Party of Lithuania and the
Democratic Labour Party of Lithuania merged. The merged party kept the Social Democratic name, but was dominated by former Democratic Labour Party members (ex-Communists). After the merger, Algirdas Brazauskas was elected leader of the Social Democratic Party. By the beginning of 2004, negotiations between the Social Democratic Party of Lithuania and various other parties to form electoral coalition. They managed to form electoral coalition called "Working for Lithuania" with their coalition partners, New Union. At the
2004 legislative elections, the Social Democratic Party of Lithuania won 20 of the 141 seats in the Seimas (other 11 seats were won by the New Union), but managed to stay at the helm of successive coalition governments, including
the minority government between 2006 and 2008. During the minority government, party's parliamentary group became the largest one in parliament, mainly due to defections from the Labour Party and the New Union (Social Liberals). Brazauskas resigned as the chairman of the party on 19 May 2007 and was replaced by
Gediminas Kirkilas. At the
2008 elections, the party won 11.73% of the national vote and 25 seats in the
Seimas, five more than in the previous elections. However, its coalition partners, the
Labour Party, the
New Union (Social Liberals) and the Lithuanian Peasants Popular Union, fared poorly and the party ended up in opposition to the
Homeland Union-led government. On 7 March 2009, the party's congress elected a new leader,
Algirdas Butkevičius. He was the party's candidate at the
2009 Lithuanian presidential election, coming in second place with 11.83% of the vote. At the
2012 parliamentary elections, the party took 38 seats and became the largest party in Parliament (although it lost in popular vote). Butkevičius became the
prime minister, forming a
coalition government with the
Labour Party,
Order and Justice and
Electoral Action of Poles in Lithuania – Christian Families Alliance. At the
2016 parliamentary elections, the party took 21 seats and formed a coalition with
Lithuanian Farmers and Greens Union. In 2017, the Social Democratic Party withdraw from coalition. In 2018, some party members left and formed the
Social Democratic Labour Party of Lithuania. After this split, the party lost a lot of support, but in 2019 it partly recovered. At the
2020 parliamentary elections, the party achieved worse results than expected. Due to this,
Gintautas Paluckas received criticism from party's board and resigned in 2021. After
a leadership election,
Vilija Blinkevičiūtė (between 2002 and 2006 she was New Union (Social Liberals) member) was elected as the new leader. After election of Blinkevičiūtė, the party's support nearly doubled thanks to her personal popularity. In the
2024 parliamentary elections, the party achieved a "historic victory", finishing in first place with 19.32% of the popular vote and 52 out of 141 seats. While party chair Vilija Blinkevičiūtė had expressed her willingness to serve as prime minister during the campaign, she declined the role after the election, leading instead to the nomination of deputy chair Gintautas Paluckas. This unexpected change in leadership was criticized by the LSDP's potential coalition partners. After the election, further controversy arose when the Social Democrats invited the newly created populist party
Dawn of Nemunas to join the ruling coalition, along with the
Union of Democrats "For Lithuania". The founder of Dawn of Nemunas,
Remigijus Žemaitaitis, is known for making antisemitic statements, and his party's inclusion sparked backlash from Lithuanian
civil society groups, as well as from lawmakers and ambassadors abroad, including
US Senate Foreign Relations Committee chair
Ben Cardin,
German MPs
Roderich Kiesewetter and
Michael Roth,
Polish senator
Michał Kamiński, and the
Israeli embassy. Roth, the chair of the
Bundestag Foreign Affairs Committee, urged the LSDP to reconsider their choice and claimed that it would threaten LSDP's membership in the
Party of European Socialists. In power, the Paluckas Cabinet raised Lithuania's defense funding to its highest level in the country's history, reformed the
retirement fund system, re-established the option for low-income families to choose a public electricity supplier, increased
child benefits and funding for education, abolished premiums for private healthcare services which are financed by the state healthcare fund, and established a road fund. On 27 June 2025, a taxation reform put forward by the Social Democrats was approved by the Seimas, which established a
progressive taxation system for personal income with three tax brackets, raised
corporate tax and established new taxes on sugar and non-life insurance. On 31 July 2025, following a series of investigative reports on his allegedly corrupt business dealings,
Gintautas Paluckas announced his resignation as prime minister and chair of the Social Democratic Party. Due to Paluckas's resignation, the LSDP first deputy chair
Mindaugas Sinkevičius became the acting chair of the party. On 4 August,
Rimantas Šadžius was appointed as the acting prime minister of Lithuania. ==Ideology and platform==