# Socialist International

The Socialist International (SI) is a political international or worldwide organisation of political parties which seek to establish democratic socialism, consisting mostly of social democratic political parties and labour organisations.
Although formed in 1951 as a successor to the Labour and Socialist International, it has antecedents in the late 19th century. The organisation currently includes 132 member parties and organisations from over 100 countries. Its members have governed in many countries, including most of Europe. In 2013, a schism in the SI led to the establishment of the Progressive Alliance.
The current secretary general of the SI is Benedicta Lasi of Ghana, the current president is the prime minister of Spain, Pedro Sánchez, and the current vice-president is Temirlan Sultanbekov of Kyrgyzstan, all of whom were elected at the last SI Congress held in Madrid, Spain, in November 2022.

## History
### First and Second Internationals (1864–1916)

The International Workingmen's Association, also known as the First International, was the first international body to bring together organisations representing the working class. It was formed in London on 28 September 1864 by socialist, communist and anarchist political groups and trade unions. Tensions between moderates and revolutionaries led to its dissolution in 1876 in Philadelphia.
The Second International was formed in Paris on 14 July 1889 as an association of the socialist parties. Differences over World War I led to the Second International being dissolved in 1916.

### Labour and Socialist International (1919–1940)

The International Socialist Commission (ISC), also known as the Berne International, was formed in February 1919 at a meeting in Bern by parties that wanted to resurrect the Second International. In March 1919, Communist parties formed the Communist International ("Comintern"), the Third International, at a meeting in Moscow.
Some parties did not want to be a part of the resurrected Second International (ISC) or Comintern. They formed the International Working Union of Socialist Parties (IWUSP, also known as Vienna International, Vienna Union, or Two-and-a-Half International) on 27 February 1921 at a conference in Vienna. The ISC and the IWUSP joined to form the Labour and Socialist International (LSI) in May 1923 at a meeting in Hamburg. The rise of Nazism and the start of World War II led to the dissolution of the LSI in 1940.

### Socialist International (1951–present)

The Socialist International was formed in Frankfurt in July 1951 as a successor to the LSI.
During the post-World War II period, the SI aided social democratic parties in re-establishing themselves when dictatorship gave way to democracy in Portugal (1974) and Spain (1975). Until its 1976 Geneva Congress, the SI had few members outside Europe and no formal involvement with Latin America. In the 1980s, most SI parties gave their backing to the Nicaraguan Sandinistas (FSLN), whose democratically elected left-wing government was subject to a campaign to overthrow it backed by the United States, which culminated in the Iran–Contra affair after the Reagan administration covertly continued US support for the Contras after such support was banned by Congress.
In the late 1970s and in the 1980s the SI had extensive contacts and discussion with the two leading powers of the Cold War period, the United States and the Soviet Union, on issues concerning East–West relations and arms control. The SI supported détente and disarmament agreements, such as SALT II, START and INF. They had several meetings and discussion in Washington, D.C., with President Jimmy Carter and Vice President George Bush and in Moscow with Secretaries General Leonid Brezhnev and Mikhail Gorbachev. The SI's delegations to these discussions were led by the Finnish Prime Minister Kalevi Sorsa.
Since then, the SI has admitted as members an increasing number of parties and organisations from Africa, Asia, Europe, and Latin America (see below for current list).
Following the Tunisian Revolution, the Constitutional Democratic Rally was expelled from the SI in January 2011; later that month the Egyptian National Democratic Party was also expelled; and as a result of the 2010–2011 Ivorian crisis, the Ivorian Popular Front was expelled in March 2011, in accordance with section 7.1 of the statutes of the Socialist International. These decisions were approved at the subsequent SI Congress in Cape Town in 2012 in line with section 5.1.3 of the statutes. These were long term ruling parties of one-party states that were overthrown in the protests of the Arab Spring.

### Progressive Alliance split (2013)

On 22 May 2013 the Social Democratic Party of Germany along with some other current and former member parties of the SI founded a rival international network of social-democratic parties known as the Progressive Alliance, citing the perceived undemocratic and outmoded nature of the SI, as well as the Socialist International's admittance and continuing inclusion of undemocratic political movements into the organization. For example, the SPD objected to the continued presence of the Sandinista National Liberation Front and the delayed ouster of the Tunisian Democratic Constitutional Rally and Egyptian National Democratic Party.
After the 2012 Congress, the SI underwent major changes as many of the large European parties allowed their membership to lapse – for example the Social Democratic Party of Germany (SPD) and the Swedish Social Democratic Party – or downgraded their membership to observer status – for example, the British Labour Party and the Norwegian Labour Party (DNA). These parties now concentrate their international links on the Progressive Alliance, with the SI's focus now increasingly being on the global south.

### Relationship with Latin America

For a long time, the Socialist International remained distant from Latin America, considering the region as a zone of influence of the United States. For example, it did not denounce the coup d'état against Socialist President Jacobo Árbenz in Guatemala in 1954 or the invasion of the Dominican Republic by the United States in 1965. It was not until the 1973 Chilean coup d'état that "a world we did not know" was discovered, explained Antoine Blanca, a diplomat for the French Socialist Party. According to him, solidarity with the Chilean left was "the first challenge worthy of the name, against Washington, of an International which, until then, had done everything to appear subject to American strategy and NATO". Subsequently, notably under the leadership of François Mitterrand, the SI supported the Sandinistas in Nicaragua and other movements in El Salvador, Guatemala, and Honduras in their struggle against US-supported dictatorships.
In the 1990s, it was joined by non-socialist parties that took note of the economic power of the European countries governed or to be governed by their partners across the Atlantic and calculated the benefits they could derive from it. During this period, "the Socialist International works in a clientist way; some parties come here to rub shoulders with Europeans as if they were in the upper class," says Porfirio Muñoz Ledo, one of the representatives of the Party of the Democratic Revolution (Mexico) at the SI. It is home to "the very centrist Argentinean Radical Civic Union (UCR); the Mexican Institutional Revolutionary Party (PRI), which was not very democratically in power for seventy years; the Colombian Liberal Party—under whose governments the left-wing formation Patriotic Union (1986–1990) was exterminated—introduced the neoliberal model (1990–1994) and to which, until 2002, Álvaro Uribe will belong". In the following decade, many left-wing parties that came to power (in Brazil, Venezuela, Bolivia, Ecuador and El Salvador) preferred to keep their distance from the SI.

## Logo

The logo is the fist and rose, based on the 1977 design by José María Cruz Novillo for the Spanish Socialist Workers' Party, itself a variant of the logo drawn by Marc Bonnet for the French Socialist Party in 1969. Variants of the emblem are or were used by several SI member parties.

## Presidents, honorary presidents and secretaries general
### Presidents

* As of 2023, there have been a total of 9 Socialist International presidents.
| No. | Portrait | Name (born–died) | Term of office | Term of office | Term of office | Political party | Political party | Congress(es) | Country | Vice-president | Vice-president |
| No. | Portrait | Name (born–died) | Took office | Left office | Time in office | Political party | Political party | Congress(es) | Country | Name | Country |
| 1 | | Morgan Phillips (1902–1963) | 3 July 1951 | 6 July 1957 | 6 years, 3 days | | Labour Party | I–IV | United Kingdom | | |
| 2 | | Alsing Andersen (1893–1962) | 6 July 1957 | 9 September 1963 | 6 years, 65 days | | Social Democratic Party of Denmark | V–VII | Denmark | | |
| 3 | | Erich Ollenhauer (1901–1963) | 9 September 1963 | 14 December 1963 † | 96 days | | Social Democratic Party of Germany | VIII | West Germany | | |
| 4 | | Bruno Pittermann (1905–1983) | 5 September 1964 | 26 November 1976 | 12 years, 82 days | | Social Democratic Party of Austria | IX–XII | Austria | | |
| 5 | | Willy Brandt (1913–1992) | 26 November 1976 | 17 September 1992 | 15 years, 296 days | | Social Democratic Party of Germany | XIII–XVIII | West Germany | | |
| 6 | | Pierre Mauroy (1928–2013) | 17 September 1992 | 10 November 1999 | 7 years, 54 days | | Socialist Party of France | XIX–XX | France | | |
| 7 | | António Guterres (b. 1949) | 10 November 1999 | 15 June 2005 | 5 years, 217 days | | Socialist Party of Portugal | XXI–XXII | Portugal | | |
| 8 | | George Papandreou (b. 1952) | 30 January 2006 | 25 November 2022 | 16 years, 300 days | | PASOK | XXII–XXV | Greece | | |
| 8 | | George Papandreou (b. 1952) | 30 January 2006 | 25 November 2022 | 16 years, 300 days | | KIDISO | XXII–XXV | Greece | | |
| 9 | | Pedro Sánchez (b. 1972) | 25 November 2022 | Incumbent | 2 years, 105 days | | Spanish Socialist Workers' Party | XXVI | Spain | Temirlan Sultanbekov | Kyrgyzstan |

### Honorary presidents

Current and honorary presidents include:
* Mustapha Ben Jafar, Tunisia
* Leonel Brizola, Brazil
* Rubén Berríos, Puerto Rico
* Philippe Busquin, Belgium
* Cuauhtémoc Cárdenas, Mexico
* Mohamed El Yazghi, Morocco
* Alan García, Peru
* Anita Gradin, Sweden
* Elazar Granot, Israel
* Tarja Halonen, Finland
* Mahamadou Issoufou, Niger
* Anker Jørgensen, Denmark
* Lionel Jospin, France
* Neil Kinnock, United Kingdom
* Horacio Serpa, Colombia
* Enrique Silva Cimma, Chile
* Mário Soares, Portugal
* Hans-Jochen Vogel, Germany

### Secretaries general

* Julius Braunthal, Austria (1951–1956)
* Bjarne Braatoy, Norway (1956–1957)
* Albert Carthy, United Kingdom (1957–1969)
* Hans Janitschek, Austria (1969–1976)
* Bernt Carlsson, Sweden (1976–1983)
* Pentti Väänänen, Finland (1983–1989)
* Luis Ayala, Chile (1989–2022)
* Benedicta Lasi, Ghana (since 2022)

## Summits

* 1951 (Ist): Frankfurt, West Germany.
* 1952 (IInd): Milan, Italy.
* 1953 (IIIrd): Stockholm, Sweden.
* 1955 (IVth): London, United Kingdom.
* 1957 (Vth): Vienna, Austria.
* 1959 (VIth): Hamburg, West Germany.
* 1961 (VIIth): Rome, Italy.
* 1963 (VIIIth): Amsterdam, Netherlands.
* 1964 (IXth): Brussels, Belgium.
* 1966 (Xth): Stockholm, Sweden.
* 1969 (XIth): Eastbourne, United Kingdom.
* 1972 (XIIth): Vienna, Austria (2nd time).
* 1976 (XIIIth): Geneva, Switzerland.
* 1978 (XIVth): Vancouver, Canada.
* 1980 (XVth): Madrid, Spain.
* 1983 (XVIth): Albufeira, Portugal.
* 1986 (XVIIth): Lima, Peru.
* 1989 (XVIIIth): Stockholm, Sweden (2nd time).
* 1992 (XIXth): Berlin, Germany.
* 1996 (XXth): New York City, United States.
* 1999 (XXIst): Paris, France.
* 2003 (XXIInd): São Paulo, Brazil.
* 2008 (XXIIIrd): Athens, Greece.
* 2012 (XXIVth): Cape Town, South Africa.
* 2017 (XXVth): Cartagena, Colombia.
* 2022 (XXVIth): Madrid, Spain (2nd time).

## Members
### Full members

There are 92 full members:
| Country | Name | Abbr | Government | Notes | Lower House | Upper House |
| Albania | Socialist Party of Albania | PS | in government | Admitted as consultative member in 1999. Promoted to full member in 2003. | 74 / 140 (53%) | 74 / 140 (53%) |
| Algeria | Socialist Forces Front | FFS | in opposition | Admitted as consultative member in 1992. Promoted to full member in 1996. | 0 / 407 (0%) | 4 / 144 (3%) |
| Andorra | Social Democratic Party | PS | in opposition | Promoted to full member in 2003. | 3 / 28 (11%) | 3 / 28 (11%) |
| Angola | Popular Movement for the Liberation of Angola | MPLA | in government | Admitted as observer member in 1996. Promoted to full member in 2003. | 124 / 220 (56%) | 124 / 220 (56%) |
| Argentina | Radical Civic Union | UCR | in opposition | Admitted as consultative member in 1996. Promoted to full member in 1999. | 34 / 257 (13%) | 13 / 72 (18%) |
| Armenia | Armenian Revolutionary Federation | ARF | in opposition | Admitted (as Armenian Socialist Party) as observer member in 1996. Promoted (as ASP) to consultative member in 1999. Promoted (as ASP) to full member in 2003. | 10 / 107 (9%) | 10 / 107 (9%) |
| Belarus | Belarusian Social Democratic Party | BSDP | extra-parliamentary | Admitted as observer member in 1999. Promoted to consultative member in 2003. Promoted to full member in November 2015. Officially deregistered in Belarus since 2005. | 0 / 110 (0%) | 0 / 64 (0%) |
| Belgium | Socialist Party | PS | in opposition}} | | 16 / 150 (11%) | 6 / 60 (10%) |
| Bolivia | National Unity Front | UN | extra-parliamentary | Promoted to full member in March 2017. | 0 / 130 (0%) | 0 / 36 (0%) |
| Bosnia and Herzegovina | Social Democratic Party of Bosnia and Herzegovina | SDP BiH | in government | Admitted as observer member in 1996. Promoted to full member in 1999. | 6 / 42 (14%) | 0 / 15 (0%) |
| Brazil | Democratic Labour Party | PDT | junior party in coalition | Admitted as consultative member in 1986. Promoted to full member in 1989. | 18 / 513 (4%) | 2 / 81 (2%) |
| Bulgaria | Party of Bulgarian Social Democrats | PBSD | extra-parliamentary | | 0 / 240 (0%) | 0 / 240 (0%) |
| Bulgaria | Bulgarian Socialist Party | BSP | in opposition | Admitted as full member in 2003. | 18 / 240 (8%) | 18 / 240 (8%) |
| Burkina Faso | People's Movement for Progress | MPP | extra-parliamentary | Admitted as full member in 2016. | 0 / 127 (0%) | 0 / 127 (0%) |
| Cameroon | Social Democratic Front | SDF | in opposition | Admitted as consultative member in 1996. Promoted to full member in 1999. | 5 / 180 (3%) | 1 / 100 (1%) |
| Cape Verde | African Party for the Independence of Cape Verde | PAICV | in opposition | Admitted as consultative member in 1992. Promoted to full member in 1996. | 30 / 72 (42%) | 30 / 72 (42%) |
| Central African Republic | Movement for the Liberation of the Central African People | MLPC | in opposition | Admitted as observer member in 2008. Upgraded to full member in 2018. | 9 / 100 (9%) | 9 / 100 (9%) |
| Chad | National Union for Democracy and Renewal | UNDR | extra-parliamentary | Admitted as observer member in June/July 2014. Upgraded to full member in 2017. | 0 / 155 (0%) | 0 / 155 (0%) |
| Chile | Party for Democracy | PPD | junior party in coalition | Admitted as consultative member in 1992. Promoted to full member in 1996. | 7 / 155 (5%) | 6 / 50 (12%) |
| Chile | Radical Party of Chile | PRSD | junior party in coalition | | 4 / 155 (3%) | 0 / 50 (0%) |
| Chile | Socialist Party of Chile | PS | junior party in coalition | Admitted as consultative member in 1992. Promoted to full member in 1996. | 13 / 155 (8%) | 7 / 50 (14%) |
| Colombia | Colombian Liberal Party | PLC | junior party in coalition | Admitted as consultative member in 1992. Promoted to full member in 1999. | 32 / 188 (17%) | 14 / 108 (13%) |
| Costa Rica | National Liberation Party | PLN | in opposition | Full member since 1987. | 19 / 57 (33%) | 19 / 57 (33%) |
| Croatia | Social Democratic Party of Croatia | SDP | in opposition | Admitted as full member in 1999. | 37 / 151 (25%) | 37 / 151 (25%) |
| Cyprus | EDEK Socialist Party | EDEK | junior party in coalition | Full member since 1987. Promoted to full member in 1992. | 3 / 56 (5%) | 3 / 56 (5%) |
| Cyprus (North) | Republican Turkish Party | CTP | in opposition | Admitted as consultative member in 2008 (pending consultation). Promoted to full member in June/July 2014. | 18 / 50 (36%) | 18 / 50 (36%) |
| Cyprus (North) | Communal Democracy Party | TDP | extra-parliamentary | Admitted as consultative member in November 2015. Promoted to full member in March 2017. | 0 / 50 (0%) | 0 / 50 (0%) |
| Czech Republic | Social Democracy | SOCDEM | in opposition | | 0 / 200 (0%) | 1 / 81 (1%) |
| Democratic Republic of the Congo | Union for Democracy and Social Progress | UDPS | in government | Admitted as observer member in 2003. | 32 / 500 (6%) | 0 / 108 (0%) |
| Dominican Republic | Dominican Revolutionary Party | PRD | in opposition | Full member since 1987. | 4 / 190 (2%) | 0 / 32 (0%) |
| Equatorial Guinea | Convergence for Social Democracy | CPDS | extra-parliamentary | Admitted as consultative member in 1996. Promoted to full member in 1999. | 0 / 100 (0%) | 0 / 100 (0%) |
| Finland | Social Democratic Party of Finland | SDP | in opposition | | 43 / 200 (22%) | 43 / 200 (22%) |
| France | Socialist Party | PS | in opposition | | 63 / 577 (11%) | 66 / 348 (19%) |
| Ghana | National Democratic Congress | NDC | Yes in government | Admitted as consultative member in 2003. Promoted to full member in 2008. | 183 / 276 (66%) | 183 / 276 (66%) |
| Greece | PASOK – Movement for Change | PASOK-KINAL | in opposition | Full member since 1990. | 32 / 300 (11%) | 32 / 300 (11%) |
| Guatemala | National Unity of Hope | UNE | in opposition | Admitted as full member in 2008. | 28 / 160 (18%) | 28 / 160 (18%) |
| Guinea | Rally of the Guinean People | RPG | in opposition | Admitted (as Guinean People's Assembly) as consultative member in 1999. Promoted (as GPA) to full member in 2003. | 1 / 81 (1%) | 1 / 81 (1%) |
| Haiti | Fusion of Haitian Social Democrats | PFSDH | extra-parliamentary | Full member since 1989. | 0 / 119 (0%) | 0 / 30 (0%) |
| Haiti | Social Democratic Assembly for the Progress of Haiti (RSD) | RSD | extra-parliamentary | Admitted as full members in 2018 | 0 / 119 (0%) | 0 / 30 (0%) |
| Hungary | Hungarian Socialist Party | MSzP | in opposition | Admitted as observer member in 1992. Promoted to full member in 1996. | 10 / 199 (5%) | 10 / 199 (5%) |
| India | Indian National Congress | INC | in opposition | Originally joined in 1993. Readmitted as full member December 2014. | 99 / 543 (18%) | 27 / 245 (11%) |
| Iraq | Patriotic Union of Kurdistan | PUK | junior party in coalition | Admitted as observer member in 2003. Promoted to full member in 2008. | 17 / 329 (5%) | 17 / 329 (5%) |
| Israel | The Democrats | הדמוקרטים | in opposition | 2024 merger of the Israeli Labor Party and Meretz. | 4 / 120 | 4 / 120 |
| Italy | Italian Socialist Party | PSI | extra-parliamentary | | 0 / 400 (0%) | 0 / 200 (0%) |
| Jamaica | People's National Party | PNP | in opposition | Full member since 1952. Temporarily demoted to observer member in 2012 due to non-payment of membership fees. | 14 / 63 (22%) | 8 / 21 (38%) |
| Japan | Social Democratic Party | SDP | in opposition | Full member since 1951 as the Japan Socialist Party. | 1 / 465 (0.2%) | 2 / 248 (0.8%) |
| Kazakhstan | Nationwide Social Democratic Party | JSDP | in opposition | Admitted as consultative member in 2012. Promoted to full member in November 2015. | 4 / 98 (4%) | 4 / 98 (4%) |
| Kyrgyzstan | Social Democrats (Kyrgyzstan) | SDK | in opposition | Legal successor to the Social Democratic Party of Kyrgyzstan. | 1 / 90 (1%) | 1 / 90 (1%) |
| Lebanon | Progressive Socialist Party | PSP | in opposition | Full member since 1980. | 8 / 128 (6%) | 8 / 128 (6%) |
| Lithuania | Social Democratic Party of Lithuania | LSDP | in government | Full member since the 1990s. | 52 / 141 (37%) | 52 / 141 (37%) |
| Luxembourg | Luxembourg Socialist Workers' Party | LSAP/POSL | in opposition | Full member since 1951. | 11 / 60 (18%) | 11 / 60 (18%) |
| Mali | Alliance for Democracy in Mali | ADEMA-PASJ | in opposition | Admitted as consultative member in 1996. Promoted to full member in 1999. Promoted to full member in 2008. Status unclear following the 2020 Malian coup d'état. | 24 / 147 (16%) | 24 / 147 (16%) |
| Mali | Rally for Mali | RPM | in opposition | Admitted as consultative member in 2003. Status unclear following the 2020 Malian coup d'état. | 51 / 147 (35%) | 51 / 147 (35%) |
| Malta | Malta Labour Party | PL | in government | Full member since 1955, leading to the entire party being interdicted by the Catholic Church in 1961. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. Rejoined in 2025. | 43 / 79 (54%) | 43 / 79 (54%) |
| Mauritania | Rally of Democratic Forces | RFD | extra-parliamentary | Admitted as observer member in 2003. Promoted to full member in 2008. | 0 / 176 (0%) | 0 / 176 (0%) |
| Mauritius | Labour Party | PTR | in government | Full member since 1969. | 35 / 66 (53%) | 35 / 66 (53%) |
| Mauritius | Mauritian Militant Movement | MMM | in government | Admitted as consultative member in 1996. Promoted to full member in 2003. Part of the Alliance of the Heart. | 19 / 66 (29%) | 19 / 66 (29%) |
| Mexico | Institutional Revolutionary Party | PRI | in opposition | Admitted as consultative member in 1996. Promoted to full member in 2003. | 68 / 500 (14%) | 13 / 128 (10%) |
| Moldova | European Social Democratic Party | PSDE | extra-parliamentary | Admitted as consultative member in 2008. Promoted to full member in 2012. Part of Alliance for European Integration. | 0 / 101 (0%) | 0 / 101 (0%) |
| Mongolia | Mongolian People's Party | MPP | in government | Admitted (as Mongolian People's Revolutionary Party) as observer member in 1999. Promoted (as Mongolian People's Revolutionary Party) to full member in 2003. | 62 / 76 (82%) | 62 / 76 (82%) |
| Montenegro | Democratic Party of Socialists of Montenegro | DPS | in opposition | Admitted as consultative member in 2003. Promoted to full member in 2008. | 17 / 81 (21%) | 17 / 81 (21%) |
| Montenegro | Social Democratic Party of Montenegro | SDP | extra-parliamentary | Admitted as observer member in 1996. Promoted to consultative member in 1999. Promoted to full member in 2003. | 0 / 81 (0%) | 0 / 81 (0%) |
| Morocco | Socialist Union of Popular Forces | USFP | in opposition | Promoted to full member in 1992. | 37 / 395 (9%) | 8 / 120 (7%) |
| Mozambique | Frelimo Party | FRELIMO | in government | Admitted as consultative member in 1996. Promoted to full member in 1999. | 184 / 250 (74%) | 184 / 250 (74%) |
| Namibia | South West Africa People's Organisation | SWAPO | in government | Promoted to full member in 2008. | 63 / 96 (66%) | 28 / 42 (67%) |
| Nepal | Nepali Congress | NC | in coalition | Admitted as consultative member in 1989. Promoted to full member in 1999. | 88 / 275 (32%) | 16 / 59 (27%) |
| Niger | Nigerien Party for Democracy and Socialism | PNDS | in opposition | Admitted as consultative member in 1996. Promoted to full member in 2003. Status unclear following the 2023 Nigerien coup d'état. | 79 / 171 (46%) | 79 / 171 (46%) |
| Pakistan | Pakistan Peoples Party | PPP | junior party in coalition | Admitted as consultative member in 1989. Promoted to full member in 2003. | 0 / 336 (0%) | 20 / 100 (20%) |
| Palestine | Fatah | | in government | Admitted as observer member in 1996. Promoted to consultative member in 1999. Promoted to full member in 2012. | 45 / 132 (34%) | 45 / 132 (34%) |
| Panama | Democratic Revolutionary Party | PRD | in government | Admitted as consultative member in 1986. Admitted as consultative member in 1996. Promoted to full member in 2003. | 35 / 71 (49%) | 35 / 71 (49%) |
| Paraguay | Progressive Democratic Party | PDP | extra-parliamentary | Admitted as consultative member in 2008. Promoted to full member in November 2015. | 0 / 80 (0%) | 0 / 45 (0%) |
| Peru | Peruvian Aprista Party | PAP | extra-parliamentary | Promoted to full member in 1999. | 0 / 130 (0%) | 0 / 130 (0%) |
| Philippines | Philippine Democratic Socialist Party | PDSP | extra-parliamentary | Admitted as consultative member in 1992. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. Reinstated in 2019. | 0 / 316 (0%) | 0 / 24 (0%) |
| Portugal | Socialist Party | PS | in opposition | | 78 / 230 (34%) | 78 / 230 (34%) |
| Puerto Rico | Puerto Rican Independence Party | PIP | in opposition | Consultative member in 1987, full member in 1994. Promoted to full member in 1992. | 1 / 51 (2%) | 1 / 27 (4%) |
| Romania | Social Democratic Party | PSD | in government | Admitted as consultative member in 1996. Promoted to full member in 1999. PSDR admitted as consultative member in 1992, full member in 2001. Admitted as full member in 2003. Both parties merged into PSD in 2001. | 107 / 330 (32%) | 49 / 136 (36%) |
| San Marino | Party of Socialists and Democrats | PSD | junior partner in coalition | Consultative member in 1961, full member in 1980. | 4 / 60 (7%) | 4 / 60 (7%) |
| Senegal | Socialist Party of Senegal | PS | junior partner in coalition | Full member since the 1970s. Boycotted last election. | 0 / 150 (0%) | 0 / 150 (0%) |
| Slovakia | Direction – Social Democracy | SMER-SD | in government | Full member. | 42 / 150 (28%) | 42 / 150 (28%) |
| South Africa | African National Congress | ANC | in government | Admitted as full member in 1999. | 159 / 400 (40%) | 43 / 90 (48%) |
| Spain | Spanish Socialist Workers' Party | PSOE | in government | Full member since 1951. | 121 / 350 (35%) | 88 / 266 (33%) |
| Tunisia | Democratic Forum for Labour and Liberties | FDTL | — | Admitted as consultative member in 2003. Demoted to observer member in 2012 due to non-payment of membership fees. Promoted to full member in 2012. Boycotted the 2022–23 Tunisian parliamentary election. | 0 / 217 (0%) | 0 / 217 (0%) |
| Turkey | Republican People's Party | CHP | in opposition | Took Social Democratic Populist Party's place in 1995. | 134 / 600 (22%) | 134 / 600 (22%) |
| Uruguay | New Space | PNE | in opposition | Admitted as consultative member in 1999. Promoted to full member in 2003.Party does not individually stand in elections but participates as part of the Broad Front. |
| Venezuela | A New Era | UNT | extra-parliamentary | Admitted as consultative member in 2013. Promoted to full member in November 2015. | 0 / 277 (0%) | 0 / 277 (0%) |
| Venezuela | Democratic Action | AD | in opposition | Observer member in 1966, consultative member in 1981, full member mid 1980s. | 11 / 277 (4%) | 11 / 277 (4%) |
| Venezuela | Popular Will | VP | extra-parliamentary | Admitted as full member in December 2014. | 0 / 277 (0%) | 0 / 277 (0%) |
| Yemen | Yemeni Socialist Party | YSP | in opposition | Admitted as observer member in 2003. Promoted to consultative member in 2008. Promoted to full member in 2012. | 8 / 301 (3%) | 8 / 301 (3%) |

### Consultative parties

There are 19 consultative parties:
| Country | Name | Abbr | Government | Notes | Lower House | Upper House |
| Botswana | Botswana Democratic Party | BDP | in opposition | Admitted as consultative member in June/July 2014. | 4 / 61 (7%) | 4 / 61 (7%) |
| Democratic Republic of the Congo | Unified Lumumbist Party | PALU | in opposition | Admitted as observer member in December 2014. Upgraded to consultative in 2019. | 17 / 500 (3%) | 2 / 108 (2%) |
| Djibouti | Movement for Democratic Renewal and Development | MRD | — | Admitted as consultative members in 2019. |
| Eswatini | People's United Democratic Movement | PUDEMO | — | Admitted as consultative member in 2013. Political parties are banned in Eswatini. |
| Gabon | Gabonese Progress Party | PGP | — | Admitted as consultative member in 1996. | 0 / 143 (0%) | 0 / 143 (0%) |
| Gambia | United Democratic Party | UDP | in opposition | Admitted as consultative member in 2012. | 15 / 58 (26%) | 15 / 58 (26%) |
| Georgia | Social Democrats for the Development of Georgia | SDD | extra-parliamentary | Admitted as consultative member in 2013. | 0 / 150 (0%) | 0 / 150 (0%) |
| Ghana | Convention People's Party | CPP | extra-parliamentary | Admitted as consultative member in 2018 | 0 / 275 (0%) | 0 / 275 (0%) |
| Guinea-Bissau | African Party for the Independence of Guinea and Cape Verde | PAIGC | in opposition | Admitted as consultative member in 2008. | 47 / 102 (46%) | 47 / 102 (46%) |
| Iran | Democratic Party of Iranian Kurdistan | PDKI | — | Admitted as observer member in 1996. Promoted to consultative member in 2008. Officially banned in Iran. |
| Iran | Komala Party of Iranian Kurdistan | KPIK | — | Admitted as observer member in 2014 Promoted to consultative member in 2018 Officially banned in Iran. |
| Palestine | Palestinian National Initiative | PNI | in opposition | Admitted as observer member in 2008. Promoted to consultative member in 2012. | 2 / 132 (2%) | 2 / 132 (2%) |
| Palestine | Palestinian Popular Struggle Front | PPSF | junior partner in coalition | Admitted as consultative member in 2018. | 0 / 132 (0%) | 0 / 132 (0%) |
| Sahrawi Republic | Polisario Front | POLISARIO | in government | Admitted as observer member in 2008. Promoted to consultative member in 2017. | 51 / 51 (100%) | 51 / 51 (100%) |
| São Tomé and Príncipe | Movement for the Liberation of São Tomé and Príncipe/Social Democratic Party | MLSTP/PSD | in opposition | Admitted as consultative member in 2013. | 18 / 55 (33%) | 18 / 55 (33%) |
| Syria | Democratic Union Party | PYD | extra-parliamentary opposition | Admitted as consultative member in November 2015. | 0 / 250 (0%) | 0 / 250 (0%) |
| Togo | Democratic Convention of African Peoples | CDPA | extra-parliamentary opposition | Admitted as consultative member in 1999. | 0 / 91 (0%) | 0 / 91 (0%) |
| Ukraine | Social Democratic Party of Ukraine | SDPU | extra-parliamentary opposition | Admitted as consultative member in 2003. | 0 / 450 (0%) | 0 / 450 (0%) |

### Observer parties

There are eight observer parties:
| Country | Name | Abbr | Government | Notes |
| Eswatini | Swazi Democratic Party | SWADEPA | — | Admitted as observer member in June/July 2014. |
| Ireland | Labour Party | | in opposition | |
| Kenya | Labour Party of Kenya | | | Admitted as observer member in 2012. |
| Kosovo | Vetëvendosje | VV | in government | Admitted as observer member in 2018. |
| Lesotho | Lesotho Congress for Democracy | LCD | junior party in coalition | Admitted as observer member in June/July 2014. |
| Serbia | Social Democratic Party of Serbia | SDPS | junior party in coalition | Admitted as observer member in 2018. |
| Somaliland | Justice and Welfare Party | JWP | in opposition | Admitted as observer member in 2013 |
| United Kingdom | Labour Party | | in government | Member since 1951. Currently holds a majority in Westminster, following the 2024 United Kingdom general election. Welsh Labour is in government in Wales and London Labour holds the London Mayoralty. The party asked to be downgraded to observer status in February 2013 "in view of ethical concerns, and to develop international co-operation through new networks." The request was accepted later that year. |
| United Kingdom (Northern Ireland) | Social Democratic and Labour Party | SDLP | in opposition | Admitted as a full member in 1974. |

### Former members

| Country | Name | Abbr | Notes |
| Albania | Social Democratic Party of Albania | PSD | Admitted as consultative member in 1992. Promoted to full member in 1996. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Algeria | National Liberation Front | FLN | Expelled following the 2019 Algerian protests. |
| Andorra | New Democracy | ND | Admitted as consultative member in 1999. |
| Antigua and Barbuda | Antigua and Barbuda Labour Party | ALP | Admitted as consultative member in 2008. |
| Argentina | Popular Socialist Party | PSP | Admitted as full member in 1992. Merged with the Democratic Socialist Party to form the Socialist Party. |
| Argentina | Socialist Party | PS | Full member since 1951. |
| Azerbaijan | Azerbaijani Social Democratic Party | ASDP | Admitted as observer member in 1996. Promoted to consultative member in 2003. Readmitted as consultative member in June/July 2014. Admitted as full member in 2016. Party dissolved in 2023. |
| Aruba | People's Electoral Movement | MEP | Promoted to full member in 1992. Full member since 1994. Delisted in December 2014. |
| Australia | Australian Labor Party | ALP | Admitted as full member in 1966. Delisted in December 2014. |
| Austria | Social Democratic Party of Austria | SPÖ | Admitted as a full member in 1951. Delisted in 2022. |
| Barbados | Barbados Labour Party | BLP | Admitted as full member in 1987. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Belgium | Belgian Socialist Party | PSB/BSP | Founder member. Split in 1978. |
| Belgium | Forward | | Delisted in 2017. |
| Benin | Democratic Union of Progressive Forces | UDFP | Admitted as observer member in 1992. |
| Benin | Social Democratic Party | PSD | Admitted as consultative member in 1999. Promoted to full member in 2003. |
| Bosnia and Herzegovina | Alliance of Independent Social Democrats | SNSD | Admitted as consultative member in 2003. Promoted to full member in 2008 Expelled in August 2012. |
| Botswana | Botswana National Front | BNF | Admitted as observer member in 1996. |
| Bolivia | Revolutionary Left Movement | MIR | Admitted as consultative member in 1986. Consultative member in 1987. Promoted to full member in 1992. |
| Bulgaria | Bulgarian Euro-Left | BEL | Admitted as observer member in 1999. |
| Burkina Faso | Party for Democracy and Progress / Socialist Party | PDP/PS | Admitted as full member circa 1995. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Burundi | Front for Democracy in Burundi | FRODEBU | Admitted as consultative member in 2003. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Canada | Co-operative Commonwealth Federation | CCF | Became the New Democratic Party in 1961. |
| Canada | New Democratic Party | NDP/NPD | Delisted in 2018. |
| Central African Republic | Movement for Democracy and Social Progress | MDPS | Admitted as observer member in 1992. |
| Iran | Kurdistan Democratic Party | KDP | Admitted as a full member in November 2015. Party dissolved in 2022. |
| Kyrgyzstan | Social Democratic Party of Kyrgyzstan | SDPK | |
| Ivory Coast | Ivorian Popular Front | FPI | Admitted as consultative member in 1992. Promoted to full member in 1996. Expelled in March 2011. |
| Colombia | Alternative Democratic Pole | PDA | Former observer member. Delisted in December 2014. |
| Colombia | M-19 Democratic Alliance | AD/M-19 | Admitted as observer member in 1992. |
| Curaçao | Partido MAN | MAN | Promoted to full member in 1989. Delisted in 2017. |
| Denmark | Social Democrats | SD | Founding member. Withdrew in 2017. |
| Dominica | Dominica Labour Party | DLP | Admitted as consultative member in 1996. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Ecuador | Democratic Left | PID | Member since 1987. Delisted in 2017. |
| Egypt | Egyptian Social Democratic Party | ESDP (or HMDI in Arabic) | Admitted as consultative member in 2012. Promoted to full member in November 2015. Delisted in 2019 due to non-payment of membership fees. |
| Egypt | National Democratic Party | NDP | Admitted as full member in 1989. Full member since 1992. Expelled in January 2011. |
| El Salvador | Democratic Party | PD | Admitted as observer member in 1996. |
| Estonia | Social Democratic Party | SDE | Member since 1990. Withdrew in 2017. |
| Fiji | Fiji Labour Party | FLP | Admitted as consultative member in 1992. Expelled in 2008, due to the party's participation in a government issued from a military coup. |
| France | French Section of the Workers' International | SFIO | Founding member. Member in 1951–1969. |
| Georgia | Union of Citizens of Georgia | CUG | Admitted as observer member in 1996. Party disbanded in 2003. |
| Germany | Social Democratic Party of Germany | SPD | Founding member. Withdrew in 2017. |
| Greenland | Siumut | | Admitted as consultative member in 1986. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Guatemala | Social Democratic Convergence | CSD | Admitted as consultative member in 2003. |
| Haiti | Party of the National Congress of Democratic Movements | KONAKOM | Admitted as consultative member in 1992. Promoted to full member in 1996. |
| Haiti | Struggling People's Organization | OPL | Admitted (as Lavalas Political Organisation) as observer member in 1996. |
| Haiti | Revolutionary Progressive Nationalist Party | PANPRA | Admitted as consultative member in 1989. Promoted to full member in 1992. |
| Hungary | Social Democratic Party of Hungary | MSZDP | Member since 1990. Admitted as observer member in 1992. Promoted to consultative member in 1999. Promoted to full member in 2003. Delisted in 2020 due to inactivity |
| Iceland | Social Democratic Party | A | Member since 1987. Formed Social Democratic Alliance in 2000. |
| Iceland | Social Democratic Alliance | S | Withdrew in 2017. |
| Iran | League of Iranian Socialists | | Joined in 1960. It was dissolved in 1980s. |
| Israel | Israeli Labor Party | Avoda | Until May 2020, it temporarily suspended membership in July 2018 over SI's adoption of BDS policies. |
| Israel | Meretz | | Merged with Israeli Labor Party to form The Democrats in 2024. |
| Italy | Democratic Party of the Left | PDS | Admitted as full member in 1992. Merged with others to form Democrats of the Left in 1998. |
| Italy | Democrats of the Left | DS | Full member since 1992 as Democratic Party of the Left. Merged with other movements to form the Democratic Party in 2007. Listed as SI member until XXIV Congress in 2012. |
| Italy | Italian Socialist Party | PSI | Party dissolved in 1994 and succeeded by the Italian Socialists (who formed the Italian Democratic Socialists in 1998 and resumed as the Italian Socialist Party in 2007). |
| Italy | Italian Democratic Socialist Party | PSDI | Founding member. Party merged into the Italian Democratic Socialists in 1998 (renamed into Italian Socialist Party in 2007). |
| Japan | Democratic Socialist Party | DSP/Minsha-tō | Admitted as SI member in 1961. Merged with non-socialist movements to form the New Frontier Party in 1994. |
| Japan | Japan Socialist Party | JSP/Shakai-tō | Admitted as SI member in 1951. Refounded as the Social Democratic Party in 1996. |
| Jordan | Jordanian Democratic Party of the Left | JDPL | Admitted as observer member in 2003. |
| Kyrgyzstan | Ata Meken Socialist Party | | Admitted as observer member in 2008. |
| Latvia | Latvian Social Democratic Workers' Party | LSDSP | Full member since 1994. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Latvia | Social Democratic Party "Harmony" | SDPS | Admitted as consultative member in June/July 2014. Withdrew in 2017. |
| North Macedonia | Social Democratic Union of Macedonia | SDSM | Admitted as observer member in 1996. Promoted to full member in 2003. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Madagascar | Party for National Unity | VITM | Admitted as consultative member in 1989. |
| Malaysia | Democratic Action Party | DAP | Full member since 1987. Delisted in 2017. |
| Mexico | Party of the Democratic Revolution | PRD | Admitted as full member in 1996. |
| Moldova | Social Democratic Party of Moldova | PSDM | Admitted as observer member in 1996. |
| Mongolia | Mongolian Social Democratic Party | MSDP | Admitted as consultative member in 1992. Promoted to full member in 1996. Merged with others in 2000 to form the Democratic Party. |
| Namibia | Congress of Democrats | CoD | Admitted as consultative member in 2003. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Netherlands | Labour Party | PvdA | Decided to minimise involvement in SI in December 2012. Delisted in December 2014. |
| New Zealand | New Zealand Labour Party | NZLP | Member since 1952. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Nicaragua | Sandinista National Liberation Front | FSLN | Expelled in January 2019 because of violation of human rights during the Nicaraguan protests |
| Nigeria | All Progressives Congress | APC | Admitted as consultative member in December 2014. |
| North Vietnam | Vietnamese Socialist Party | | Consultative member between 1955 and 1969. |
| Norway | Labour Party | DNA | Member since 1951. Withdrew in 2016. |
| Paraguay | Party for a Country of Solidarity | PPS | Admitted as consultative member in 2003. Promoted to full member in 2008. |
| Paraguay | Revolutionary Febrerista Party | PRF | Admitted as full member in the 1970s. |
| Philippines | Akbayan | | Admitted as consultative member in 2003. |
| Poland | Democratic Left Alliance | SLD | Full member since 1996. Withdrew in 2017. |
| Poland | Labour Union | UP | Admitted as full member in 1996. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Poland | Social Democracy of the Republic of Poland | SdRP | Admitted as full member in 1996. Absorbed into the Democratic Left Alliance in 1999. |
| Romania | Democratic Party | PD | Admitted as consultative member in 1996. Promoted to full member in 1999. Merged with the Liberal Democratic Party to form the Democratic Liberal Party. |
| Russia | A Just Russia — Patriots — For Truth | SRZP | Admitted as observer member in 2008. Promoted to consultative member in 2010. Promoted to full member in 2012. Expelled in March 2022 for its support for the Russian invasion of Ukraine. |
| Russia | Social Democratic Party of Russia | SDPR | Admitted as consultative member in 2003. |
| Saint Kitts and Nevis | Saint Kitts and Nevis Labour Party | SKNLP | Admitted as consultative member in 1992. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Saint Lucia | Progressive Labour Party | | Expelled in 1992. |
| Saint Lucia | Saint Lucia Labour Party | SLP | Admitted as consultative member in 1992. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Saint Vincent and the Grenadines | Saint Vincent Labour Party | SVGLP | Admitted as consultative member in 1989. Merged with the Movement for National Unity in 1994 to form the Unity Labour Party. |
| Saint Vincent and the Grenadines | Unity Labour Party | ULP | Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Serbia | Democratic Party | DS | Admitted as consultative member in 2003. Promoted to full member in 2008. |
| Serbia | Social Democratic Party | SDP | Admitted as consultative member in 2003. Promoted to full member in 2008. Demoted to observer member in 2012 due to non-payment of membership fees. Ceased to exist in 2009 |
| Singapore | People's Action Party | PAP | Resigned in 1976 in response to the Dutch Labour Party's charges of violations of human rights and detention of political prisoners without trial, and DLP and the British Labour Party's charges of media censorship. |
| Slovakia | Party of the Democratic Left | SDĽ | Admitted as full member in 1996. Merged with Direction – Social Democracy in 2005. |
| Slovakia | Social Democratic Party of Slovakia | SDSS | Admitted as full member in 1992. Merged with Direction – Social Democracy in 2005. |
| Slovenia | Slovenian Democratic Party | SDS | Admitted (as the Social Democratic Party of Slovenia) as observer member in 1992. |
| Slovenia | Social Democrats | SD | Admitted (as United List of Social Democrats) as full member in 1996. Demoted to observer member in 2012 due to non-payment of membership fees. Delisted in December 2014. |
| Sweden | Swedish Social Democratic Party | SAP | Withdrew in March 2017. |
| Switzerland | Social Democratic Party of Switzerland | SP/PS | Withdrew in 2017. |
| Tanzania | Chama Cha Mapinduzi | CCM | Admitted as full member in 2013. |
| Timor-Leste | Revolutionary Front for an Independent East Timor | FRETILIN | Admitted as consultative member in 2003. |
| Tunisia | Democratic Constitutional Rally | RCD | Admitted as full member in 1989. Full member since 1993. Expelled in January 2011. |
| Tunisia | Popular Unity Movement | MUP | Admitted as consultative member in 1989. |
| Turkey | Democratic Left Party | DSP | Admitted as consultative member in 1986. Expelled in 1992. |
| Turkey | Democratic People's Party | DEHAP | Admitted as observer member in 2003. Merged with the Democratic Society Movement to form the Democratic Society Party which in turn was succeeded by the Peace and Democracy Party. |
| Turkey | Social Democracy Party | SODEP | Full member since 1990. Merged with the Republican People's Party in 1995. |
| Turkey | Social Democratic Populist Party | SHP | Admitted as consultative member in 1986. Promoted to full member in 1989. Merged with the Republican People's Party in 1995. |
| Ukraine | Socialist Party of Ukraine | SPU | Admitted as consultative member in 2003. Expelled in July 2011. |
| United States | Democratic Socialists of America | DSA | Had been a member of SI since founding in 1982, withdrew in August 2017. |
| United States | Democratic Socialist Organizing Committee | DSOC | Member since 1976, merged with the New American Movement in 1982 to form the Democratic Socialists of America, which remained a member until 2017. |
| United States | Social Democrats, USA | SDUSA | Member since 1972. Withdrew in 2005. |
| Uruguay | Party for the Government of the People | PGP | Admitted as consultative member in 1992. Merged with the Colorado Party in 1994. |
| Uruguay | Socialist Party of Uruguay | PSUA | Admitted as full member in 1999. Withdrew in 2017. |
| Venezuela | For Social Democracy | PODEMOS | Admitted as consultative member in 2008. |
| Venezuela | Movement for Socialism | MAS | Admitted as consultative member in 2003. |
| Zambia | Patriotic Front | PF | Admitted as consultative member in 2013. |
| Zimbabwe | Movement for Democratic Change | MDC | Admitted as full member in 2008. Delisted in 2017. |

## Fraternal organisations

* International Falcon Movement – Socialist Educational International
* Socialist International Women

## Associated organisations

* Arab Social Democratic Forum, ASDF
* Euro-Latin American Forum of Progressive and Socialist Parliamentarians
* International Federation of the Socialist and Democratic Press
* International Jewish Labor Bund
* International Labour Sports Confederation
* International League of Religious Socialists
* International Social Democratic Union for Education
* World Labour Zionist Movement, WLZM
* National Democratic Institute
* Party of European Socialists
* Social Democratic Group of the Latin American Parliament