All articles A–Z
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Social Democratic Party (UK, 1990–present)
The Social Democratic Party (SDP) is a minor British party, the 1990 continuation of the original 1981 SDP after the Liberal merger. Revived from 60 members in 2017, it won 33,811 votes in 2024 and allied with Reform UK.
Social Democratic Party (UK)
Social Democratic Party (SDP), British party founded 26 March 1981 by Labour defectors the Gang of Four; allied with the Liberals, won 25.4% in 1983, merged into the Liberal Democrats in 1988; a separate SDP led by William Clouston exists today.
Social Democratic Party (社民党) (Japan)
Social Democratic Party (社会民主党, Shamintō), successor of the Japan Socialist Party founded in 1945; main opposition 1955–1993, governed in 1990s coalitions under Murayama, then declined to a minor anti-constitutional-revision party.
Social Democratic Party of America
Social Democratic Party of America (SDP), founded 1898 by Victor Berger after splitting from Debs's Social Democracy of America; ran Debs for president in 1900 (about 97,000 votes) and merged into the Socialist Party of America in 1901.
Social Democratic Party of Austria
The Social Democratic Party of Austria (SPÖ, Sozialdemokratische Partei Österreichs), Austria's center-left party founded at Hainfeld in 1888/89 by Victor Adler, banned 1934, refounded 1945, led by Andreas Babler and in the 2025 ÖVP-SPÖ-NEOS coalition.
Social Democratic Party of Bosnia and Herzegovina
SDP BiH (Socijaldemokratska partija Bosne i Hercegovine) is Bosnia and Herzegovina's social democratic, officially multi-ethnic centre-left party, founded 1909 and re-established 1991 as successor of the League of Communists' BiH branch, led by Nermin Nikšić, with support mainly among Bosniaks.
Social Democratic Party of Croatia and Slavonia
The Social Democratic Party of Croatia and Slavonia, founded in Zagreb in 1894, was the first Slavic social democratic party in Austria-Hungary, organized on the German Social Democrats' Erfurt program.
Social Democratic Party of Finland
Social Democratic Party of Finland (Suomen Sosialidemokraattinen Puolue, SDP), founded 1899 in Turku, is Finland's historic social democratic party with about 30,000 members, led by Antti Lindtman since 2023, and biggest party in the 2025 municipal elections.
Social Democratic Party of Germany
SPD (Sozialdemokratische Partei Deutschlands), Germany's center-left social democratic party founded 1875; four chancellors including Scholz; in government 23 of 27 years to 2024 but fell to a record-low 16.4% in the 2025 election.
Social Democratic Party of India
Social Democratic Party of India (SDPI), founded 21 June 2009 in New Delhi and registered with the Election Commission on 13 April 2010, is a party for Muslims, Dalits, Backward Classes and Adivasis, widely described as the political front of the banned Popular Front of India and under ED funding scrutiny.
Social Democratic Party of Madagascar
The Social Democratic Party of Madagascar (French: Parti social-démocrate malgache, PSD) is a political party founded in 1956 by Philibert Tsiranana, who ruled the First Republic until its fall in 1972.
Social Democratic Party of Switzerland
Social Democratic Party of Switzerland (SP/PS, Sozialdemokratische Partei der Schweiz): Switzerland's leading left-wing party, founded 1888, holding 41 National Council seats and two Federal Council seats, favoring a strong welfare state and EU ties.
Social Democratic Populist Party (Turkey)
Sosyaldemokrat Halkçı Parti (SHP), Turkey's Social Democratic Populist Party, 1985 merger of SODEP and HP led by Erdal İnönü; main opposition 1987, DYP coalition partner 1991-1995, merged into CHP 1995.
Social Democratic Workers' Party of Germany
Social Democratic Workers' Party of Germany (Sozialdemokratische Arbeiterpartei, SDAP), the 'Eisenachers': socialist party founded August 1869 in Eisenach by Bebel and Liebknecht; merged with the ADAV at Gotha in 1875 to form the SAP, later the SPD.
Social Democrats (Denmark)
Socialdemokratiet (Social Democrats, letter A) is Denmark's centre-left social democratic party, founded 1871, largest party 1924-2001, led by Mette Frederiksen since 2015; won 21.9 percent and 38 seats in 2026.
Social Democrats (Ireland)
The Social Democrats (Na Daonlathaigh Shóisialta) are an Irish centre-left party founded in 2015 by Murphy, Shortall, and Donnelly; led by Holly Cairns since 2023, holding 11 Dáil seats after the 2024 election.
Social Democrats (Slovenia)
The Social Democrats, or Socialni demokrati, are a center-left social-democratic party in Slovenia, founded in 1993 as the United List of Social Democrats and renamed in 2005.
Social Democrats, USA
Social Democrats, USA (SDUSA), successor to the Socialist Party of America renamed in December 1972 by a 72-34 convention vote; a small anticommunist social democratic group led by Gershman, Kahn, Horowitz, and Rustin, influential in the AFL-CIO and NED, distinct from Harrington's DSOC, which became the DSA.
Social desirability bias
Social desirability bias is the tendency of survey respondents to answer in socially acceptable ways rather than truthfully, underreporting drug use and overstating voting or church attendance.
Social determinants of health
Social determinants of health (SDOH) are the non-medical conditions in which people are born, grow, live, work, and age, plus the wider forces shaping them; they drive health inequities, including an 18-year life expectancy gap between high- and low-income countries.
Social development theory
Social development theory covers two literatures: psychological theories of children's social relationships and understanding (Vygotsky's ZPD, Erikson, Piaget), and development-studies frameworks linking economic and social progress (Midgley, Jacobs and Cleveland), plus the Catalano-Hawkins social development model.
Social discount rate
The social discount rate is the rate used in public cost-benefit analysis to convert future costs and benefits into present values, prescribed by governments at about 1% to 8%.
Social Distance
Social Distance is a 2020 Netflix anthology series created by Hilary Weisman Graham with Jenji Kohan, eight remotely produced episodes about people staying connected through technology during the COVID-19 quarantine.
Social distancing
Social distancing, also called physical distancing, is a public health measure reducing disease transmission by limiting contact between people. Covers its 1963 term origin, 1377 quarantine roots, 1918 flu evidence, WHO 1-meter guidance, and measured COVID-19 effects.
Social Distortion
Social Distortion is an American punk rock band formed in 1978 in Fullerton, California, around Mike Ness. Known for blending punk with country and blues, it was the first original Orange County punk band to sign with a major label, Epic.
Social documentary photography
Social documentary photography records human life and living conditions to reveal social injustice and advocate reform, differing from photojournalism in running for years on social issues rather than breaking news.
Social drama
Social drama (German: Soziales Drama) is a stage drama treating the living conditions of the lower classes, closely tied to Naturalism and the industrial revolution.
Social ecological model
The social ecological model (SEM), also called socio-ecological model, is a multilevel public health framework with individual, interpersonal, organizational, community, and policy levels, rooted in Bronfenbrenner's ecological theory.
Social engineering (security)
Social engineering, also called social hacking, is the use of deception to trick people into revealing sensitive information or committing fraud instead of exploiting technology.
Social enterprise
A social enterprise is an organization that covers most of its costs through business revenue while pursuing a social mission, and may be for-profit or nonprofit.