The Croatian Left has consisted of a broad range of individuals, groups, and political parties who seek egalitarian, economic, social and cultural rights in Croatia. Left-wing ideologies came to Croatia in the late 19th century during the Austria-Hungary regime. In 1894, the Social Democratic Party of Croatia and Slavonia was formed. It was the first workers party in Croatia at the time. In the Kingdom of Serbs, Croats and Slovenes the leftist movement grew but it was suppressed by the royal government. In 1920, the Communist Party of Yugoslavia was proclaimed illegal and its sympathizers were brutally persecuted after winning a large number of positions in the local elections. During the 1920s, Stjepan Radić and his Croatian Peasant Party led a centre-left agrarianism and anti-royalist policy. They were the leading Croatian political party at the time. After the assassination of Radić in 1929, the Croatian Peasant Party was taken over by Vlatko Maček who enforced a more conservative and nationalist rhetoric. During the Socialist Yugoslavia era, the League of Communists of Yugoslavia was the only legal party in the country. In 1990, political plurality was restored and a number of left-wing parties emerged with the most notable one being the Social Democratic Party of Croatia.

Origins Marxist and socialist ideologies emerged in Croatia during the late 19th century while it was under the rule of the Austria-Hungary empire. In 1894, the Social Democratic Party of Croatia and Slavonia was formed. It was the first workers party of its kind in Croatia at the time. Its main ideology was Austromarxism so it mainly attracted local German settlers in Croatia. In 1910, Josip Broz Tito was a member of the party. Due to its Austromarxist ideology, the party was marginalised and banned after World War I started.

When the Kingdom of Serbs, Croats and Slovenes was created after World War I, the different social democratic parties that had existed in Austria-Hungary, Serbia and Montenegro called for a unification of their parties. In 1919, a congress was held in Belgrade where Bolshevik influence was introduced by soldiers who during the war had been captured by Russian forces and had experienced the October Revolution. It resulted in the creation of the Communist Party of Yugoslavia. In 1920, the Communists won a large number of seats in the local election which resulted in their banning by the royal government. It was then when the Communist members and sympathisers started working underground until 1941.

During the 1920s, Stjepan Radić and his Croatian Peasant Party were the leading political force amongst the Croatian population in the kingdom. Radić led an agrarianist, anti-royalist and anti-clerical policy. His politics at the time were considered to be left-leaning. In 1929, Radić was assassinated in Parliament, after which the King Alexander I of Yugoslavia abolished the constitution, dissolved parliament, and declared a royal dictatorship, changing the country into the first Yugoslavia and oppressing national sentiments. After the death of Radić, Vlatko Maček became president of the Croatian Peasant Party and he enforced a more conservative and nationalist policy which was mostly aimed at creating an Independent Croatian nation-state while social issues were put aside.

During World War II, while the Nazi puppet controlled Independent State of Croatia and Italy occupied modern Croatia territory, the only anti-fascist organised movement were the Yugoslav partisans who were created and led by the Communist Party of Yugoslavia and their commander Josip Broz Tito. In 1945, after the partisans won the war, Socialist Yugoslavia was established with a one-party system in which the Communist Party of Yugoslavia was the only legal political party. From 1945 to 1989, political plurality was suppressed in Yugoslavia and the League of Communists controlled the country with their bureaucratic-dogmatic approach.

It was during the era of Socialist Yugoslavia that the Socialist Republic of Croatia enacted a number of progressive and left-wing reforms such as the emancipation of women, egalitarianism, creation of a welfare state, universal health care, workers' self-management etc.

Croatian left during the first elections and creation of modern Croatia In the late 1980s, Socialist Yugoslavia was on the edge of breakup after Slobodan Milošević started his anti-bureaucratic revolution and used Serbian nationalism as a tool to achieve domination in the country. This movement sparked Croatian nationalism which would result in the rise of right-wing populism in Croatia.

In 1989, the League of Communists of Croatia declared that the first democratic elections would be held next year and that political plurality was restored. The first newly established left-wing party were the Social Democrats of Croatia. It was a social democratic-oriented party led by Antun Vujić, a Croatian Spring dissident. For the 1990 elections, he joined the coalition of liberal and moderate conservative parties called the Coalition of People's Accord. Vujčić won a seat in the parliament but the coalition won only 11 seats.

After the League of Communists of Croatia withdrew from the 14th SKJ party congress in January 1990 under the leadership of Ivica Račan, they decided to pursue a path of reformation. The party was renamed to League of Communists of Croatia-Party of Democratic Change. For the 1990 elections, Ivica Račan was not able to defeat the emerging right wing party of Franjo Tuđman, the Croatian Democratic Union. In the elections, Ivica Račan and his party won only 73 seats in the parliament while Franjo Tuđman won 205. Before the elections, Ivica Račan changed the electoral system for the benefit of his party but it backfired and the Croatian Democratic Union won a great majority of seats with only 41.76% of the popular vote. After the elections, numerous League of Communist members left the party and went to join the party of Franjo Tuđman. It is thought that about 70,000 former communists joined the Croatian Democratic Union.

On 3 November 1990, the League of Communists of Croatia held a convention where they changed their name to the Social Democratic Party of Croatia. They accepted a social-democratic platform with the rejection of socialism and Marxism. They also published the November Declaration where they condemned all the crimes that their party committed during the era of Federal Yugoslavia.

Croatia declared independence on 25 June 1991 and at the time the war in Croatia was starting to heat up against the self-proclaimed Serb parastate called Republic of Serbian Krajina. Since the Social Democratic Party got a lot of votes from Serbs in that self-proclaimed territory, it meant that Ivica Račan was about to face a great downfall in popular support.

Croatian left during the 1990s From 1991 to 1992, the Social Democratic Party and Social Democrats of Croatia were a part of the National Union government which was created by Franjo Tuđman during the first stages of the war.

The 2nd elections took place on 2 August 1992. The president and parliament were both elected on the same day. For the presidential elections, the Social Democratic Party supported Silvije Degen, president of the Socialist Party of Croatia, a minor left-wing party. Silvije Degen finished 5th with 4,1% of the popular vote while Franjo Tuđman won with a majority of 56.73% of the vote. Antun Vujić was also the candidate for president but finished last with only 0,7% of the vote. On the parliamentary elections, the Social Democratic Party won only 3 seats with 5.52% of the popular vote butgot 11 thanks to the Serb minority seats in parliament which were guaranteed by the constitution. The Social Democratic Union won 1.2% which was a great result for such a party. The Social Democratic Union was led by the famous economist Branko Horvat and the votes were a result of support from the ethnic Serbs living in the government-controlled territory. The Social Democrats of Croatia won only 0,6% of the vote.Nohlen, D & Stöver, P (2010) Elections in Europe: A data handbook, p410

After Franjo Tuđman won the presidential and parliamentary elections with a big majority, he easily imposed his will on the government controlled institutions and companies. That era is commonly known in Croatia as Tudjmanism. It commonly refers to the corrupt system of privatization, nepotism in appointing personnel to high state functions, anti-liberalism, international isolation, embracing of extreme Croatian nationalism, state-controlled media and abuse of human rights.

During that time, Ivica Račan and the Social Democratic Party tried to get rid of the perception that they were the successor party of the League of Communists. Račan tried to maintain good relations with Tuđman and at the same time act as an opposition to him. This, of course, did not resonate with the public and they stayed marginalised. The opposition at the time was ignored by the state-controlled mainstream media. In the Croatian Parliament, the most aggressive Tuđman critic was Vladimir Bebić, a famous left-wing politician from the Alliance of Primorje-Gorski Kotar.

In 1994, a former dissident and high ranking communist politician, Mika Tripalo founded Social Democratic Action of Croatia. His goal was to unite all the Croatian left parties. After a heated polemic with Ivica Račan, the Social Democratic Party declined the invitation because they wanted to become the only leading left party. The same year, Antun Vujić joined the Social Democratic Party and his party of the Social Democrats of Croatia merged with them.

The Social Democratic Party supported Stjepan Mesić and Josip Manolić in 1994 when they tried to split a number of parliamentary members from the Croatian Democratic Union in order to spark new elections. They were fierce opponents of the Croat–Bosniak War in Bosnia and Herzegovina which was organised by Franjo Tuđman and Gojko Šušak. The plan eventually failed with Mesić and Manolić becoming marginalised.

The third Croatian parliamentary elections were held in October 1995. Franjo Tuđman held the election a year early because he wanted to use the euphoria which was present in the country due to the success of Operation Storm. The Social Democratic Party won 8.93% of the popular vote and got 10 seats in parliament. The Social Democratic Union which was now allied with Vladimir Bebić won 3.24% of the vote but did not enter Parliament. Miko Tripalo's Social Democratic Action won only 1.57% of the vote. A year later, Miko Tripalo died and the party was taken over by Silvije Degen but it slowly faded into obscurity.

In 1997, former minister of culture in SR Croatia and Vice-President of the Presidency of SFR Yugoslavia, Stipe Šuvar founded the Socialist Labour Party of Croatia. It was the first democratic socialist party in modern Croatia. Šuvar was a strong critic of the Tuđman regime and he spoke about the war crimes that the Croatian Army committed after liberating Kninska Krajina in 1995. While dining in a restaurant with his wife in Zagreb, Šuvar was brutally attacked and suffered heavy injuries because of his political views.

For the 1997 presidential elections, the Social Democratic Party supported Zdravko Tomac as their candidate. Zdravko Tomac was a Croatian nationalist with social tendencies and Ivica Račan used him through the 1990s in order to get votes from centrist or right-wing voters. It proved useful in a short run but it failed on a long-term scale. Zdravko Tomac finished 2nd in the elections with 458,172 votes or 21.0%. Tuđmdan dominated the elections with 61.4% of the vote but Tomac defeated Vlado Gotovac, a candidate for the main opposition party, the Croatian Social Liberal Party who finished 3rd.