The roots of Tautas Saskaņas Partija lie within the moderate wing of Tautas Fronte, the Latvian independence movement of late 1980s and early 1990s. Its leader, Jānis Jurkāns, was the first minister of foreign affairs of newly independent Latvia, from 1990 to 1992 when he had to leave the government for his stance on relations with Russia. Together with other activists, Jurkāns founded the Saskaņa Latvijai - Atdzimšana Tautsaimniecībai alliance, which won 13 seats (out of 100) in 1993 parliamentary election. The alliance split in 1994, and one of its two parts became what is now known as the National Harmony Party (Tautas Saskaņas Partija). Jānis Jurkāns served as its leader from then until 2005, when he resigned. The party's chairman as of 2007 is Jānis Urbanovičs.
Since foundation, Tautas Saskaņas Partija was popular with ethnically Russian voters for its moderate views on issues of citizenship and state language. Unlike the other parties popular with Russians, it also had a considerable amount of ethnic Latvians in its leadership and was attempting to bridge the gap between the two communities. It won 6 seats during 1995 parliamentary election. In 1998, it allied with two other predominantly Russian parties, Latvian Socialist Party and Equal Rights (Līdztiesība), both of which held more radical pro-Russian positions. This step seriously damaged the reputation of Tautas Saskaņas Partija among ethnic Latvians. The three parties founded the Par Cilvēka Tiesībām Vienotā Latvijā (For Human Rights in United Latvia) alliance. At the legislative elections, on 5 October 2002, the alliance won 18.9 % at the popular vote, gaining 25 of the 100 seats in the Saeima. In 2003, Tautas Saskaņas Partija left the alliance. It won no seats during the European Parliament elections in 2004, and in 2005 also lost its representation at the Riga City council. In 2005 the party entered the alliance "Harmony Centre", as did the Socialist Party, one of its former partners in the Human Rights Party. Harmony Center won 17 seats in the 2006 elections.
Tautas Saskaņas Partija identifies as a social democratic party. It supports further liberalization of the citizenship law by granting citizenship to each non-citizen who has lived in Latvia for at least 10 years. (The present law only allows most of them to apply for citizenship through the process of naturalization). It also supports expanding education in minority languages (mainly Russian).