The Social Democratic Party "Harmony" (Latvian: Sociāldemokrātiskā Partija "Saskaņa", SDPS, Russian: Социал-демократическая партия «Согласие»), also commonly referred to as Harmony (Saskaņa), is a social-democratic political party in Latvia. It is the major catch-all party of the centre-left in Latvian politics. The party was founded in 2010 as the merger of the National Harmony Party (TSP) with New Centre (JC) and the Social Democratic Party (SDP), a breakaway from the Latvian Social Democratic Workers' Party (LSDSP). At that time, all three were members of the former electoral alliance Harmony Centre. The alliance also included the communist Socialist Party of Latvia. The Daugavpils City Party merged into the party in 2011.
The chairman of the party, Nils Ušakovs is the current Mayor of Riga and was the "Harmony" candidate for the office of Prime Minister of Latvia in 2014. In the Saeima the party has 24 out of 100 seats after polling 23% of the vote at the 2014 parliamentary election. Its parliamentary group is therefore the largest among the six groups in the Latvian Parliament, and the leading opposition group. Internationally, "Harmony" is a member of the Progressive Alliance and has associate status in the Party of European Socialists. Its sole MEP, Andrejs Mamikins, sits in the Progressive Alliance of Socialists and Democrats (S&D) group in the European Parliament.
"Harmony" is currently the governing party on the Riga City Council in coalition with Proud to serve Riga, the successor to the centre-right Latvia's First Party/Latvian Way which dissolved in 2011. "Harmony" is the largest party seeking to represent the Russian-speaking population of Latvia.