The Social Democratic Party of Austria (German: Sozialdemokratische Partei Österreichs [soˈtsi̯aːldemoˌkraːtɪʃɛ parˌtaɪ ˈøːstɐraɪçs], SPÖ) is a social democratic political party in Austria. Founded in 1889 as the Social Democratic Workers' Party of Austria (German: Sozialdemokratische Arbeiterpartei Österreichs, SDAPÖ) and later known as the Socialist Party of Austria (German: Sozialistische Partei Österreichs) from 1945 until 1991, the party is the oldest extant political party in Austria. Along with the Austrian People's Party (ÖVP), it is one of the country's two traditional major parties. It is positioned on the centre-left on the political spectrum.
Since June 2023, the party has been led by Andreas Babler. It is currently the third largest of five parties in the National Council, having won 41 of 183 seats and 21.1% of the popular vote in the 2024 Austrian legislative election. It holds seats in the legislatures of all nine states; of these, it is the largest party in three (Burgenland, Carinthia, and Vienna.) The SPÖ is supportive of Austria's membership in the European Union, and it is a member of the Progressive Alliance and Party of European Socialists. It sits with the Progressive Alliance of Socialists and Democrats in the European Parliament; of Austria's 19 MEPs, five are members of the SPÖ. The party has close ties to the Austrian Trade Union Federation (ÖGB) and the Austrian Chamber of Labour (AK).