The Social Democrats (Danish: Socialdemokratiet [soˈɕɛˀlte̝moˌkʰʁɑˀtɪət], lit. 'The Social Democracy', S) is a social democratic political party in Denmark. A member of the Party of European Socialists, the Social Democrats have 50 out of 179 members of the Danish parliament (following the latest Danish general election held in 2022), Folketing, and three out of fourteen MEPs elected from Denmark.

Founded by Louis Pio in 1871, the party first entered the Folketing in the 1884 Danish Folketing election. By the early 20th century, it had become the party with the largest representation in the Folketing, a distinction it would hold for 77 years. It first formed a government after the 1924 Danish Folketing election under Thorvald Stauning, the longest-serving Danish Prime Minister of the 20th century. During Stauning's government which lasted until the 1926 Danish Folketing election, the Social Democrats exerted a profound influence on Danish society, laying the foundation of the Danish welfare state. From 2002 to 2016, the party used the name Socialdemokraterne in some contexts. The party was a member of the Labour and Socialist International from 1923 to 1940. A member of the Socialist International until 2017, the party withdrew to join the Progressive Alliance, founded in 2013.

The party was the major coalition partner in government from the 2011 Danish general election until the 2015 Danish general election, with then-party leader Helle Thorning-Schmidt as Prime Minister. After losing power in the 2015 election, Thorning-Schmidt was succeeded as party leader on 28 June 2015 by the former Vice Leader Mette Frederiksen, who shifted the party back to the political left on economics, while criticising mass immigration. Frederiksen led the party to win the 2019 and 2022 Danish general election, forming a single-party minority government from 2019 to 2022 and a majority grand-coalition government with the centre-right Venstre and the centrist Moderates since 2022.

The party traces its own history back to the International Labour Association, founded in 1871 and banned in 1873, loosely re-organised in the Social Democratic Labour Party which in 1876 issued the Gimle program, but as a formal political party it was first founded from 11–12 February 1878 as the Social Democratic Federation. This name was formally carried by the party for almost a hundred years, although in practice it also used a number of other names until it changed its name to Social Democracy in 1965. At a congress in Aalborg in 2002, the party changed its name to the Social Democrats, but from 2016 again only Social Democracy is used.

The party has the letter A as a symbol, but the abbreviation S is often used in the media. The party's classic symbol is a red rose and in recent times an A in a red circle. Aside from the classical socialist red colour, the party has recently adopted a more light red colour called competition orange.

The party was a member of the Labour and Socialist International between 1923 and 1940. It is now a member of the Progressive Alliance, an association of progressive social-democratic parties. The Social Democrats are also a member of the Party of European Socialists while the party's MEPs sit in the Socialists & Democrats group.

The party was founded as the International Labour Association of Denmark on 15 October 1871 by Louis Pio, Harald Brix and Paul Geleff. The goal was to organise the emerging working class on a democratic and socialist basis. The industrialisation of Denmark had begun in the mid-19th century and a period of rapid urbanisation had led to an emerging class of urban workers. The social-democratic movement emerged from the desire to give this group political rights and representation in the Folketing, the Danish parliament. In 1876, the party held an annual conference, adopting the first party manifesto.

The stated policy was as follows: