The political system of Croatia is based on the principle of the division of power between the legislative, executive and judicial branches. The Constitution confirms that the people have the power to elect their own representatives by direct election, and the guaranteed right to local and regional self-government. Croatia is one of the rare states which have, in only two decades, implemented the majority model and the proportional representation model as well as combinations of these.
The first multiparty elections, held in 1990, had two rounds, where represntatives were elected by majority vote. Early elections in 1992 were held according to the combined electoral model. The early elections of 1995 were also held according to the combined system, but the proportion of majorities and party seats was changed. In those elections, non-resident Croatian citizens (the diaspora) were allowed to participate for the first time in a separate constituency, which elected 12 representatives. National minority representatives were elected by a relative majority of votes from among individual candidates. In the year 2000, elections were held according to the proportional representation system in 10 constituencies. From 1990 to 2000, two rounds of elections were held for the Chamber of Counties (1993 and 1997) according to the system of proportional representation, in which each county formed an electoral constituency with three mandates, and seats were distributed according to the d'Hondt formula.
According to the current law, representatives are elected to a single chamber of Parliament (Sabor), according to the proportional representation system, in 12 constituencies. In 10 constituencies, 14 representatives are elected, while the diaspora constituency elects up to 3 representatives, and the national minorities constituency elects 8. Seats are distributed according to the d'Hondt method and the electoral threshold is 5%.
In the Republic of Croatia, direct presidential elections are held in two rounds of voting; if no candidate secures a simple majority of votes in the first round, the two candidates who secured the highest number of votes go into the second round (run-off election). Direct elections are also held for municipal and city mayors and county prefects. Elections to the European Parliament were held for the first time in April 2013.
The first political parties in Croatia emerged in the second half of the 19th century, during the Habsburg Monarchy. They were elite parties, such as the National Party, the Unionist Party, the Party of the Right and others, and were primarily concerned with matters of the statehood and political status of Croatia within the Monarchy. The first modern mass political party was the Croatian Peasant Party (HSS), which grew out of the Croatian People's Peasant Party (HPSS), founded by the brothers Antun and Stjepan Radić. The HSS was the largest Croatian party in the first half of the 20th century, particularly between the two World Wars. Under the Socialist regime (1945–90), the only party operating was the Croatian Communist Party (later the Croatian League of Communists), which was part of the Yugoslav Communist Party. In the atmosphere of democratisation in the late 1980s, the League of Communists was reformed into the Democratic Change Party, then into the Social Democrat Party of Croatia (SDP). The first political opposition parties also emerged at this time, among whom were the Croatian Democratic Union (HDZ) and the Croatian Social Liberal Alliance (HSLS), who fought the first free elections held in 1990 as part of the multiparty Coalition of National Agreement. At those elections, the HDZ won, becoming the dominant party in the period of the establishment of an independent Croatian state and the democratic political order in the 1990s. The number of parties grew in the 1990s and the 2000s; at the beginning of 2019, there were 164 political parties registered in Croatia, of which 21 are parliamentary.
The Croatian party system is also characterised by parties representing national minorities, and regional parties representing the interests of particular regions of the country.