A part of the Roman province of Pannonia, Croatia was settled in the 7th cent. by Croats, who accepted Christianity in the 9th cent. A kingdom from the 10th cent., Croatia conquered surrounding districts, including Dalmatia, which was chronically contested with Venice. Croatia's power reached its peak in the 11th cent., but internecine strife facilitated its conquest in 1091 by King Ladislaus I of Hungary.

In 1102 a pact between his successor and the Croatian tribal chiefs established a personal union of Croatia and Hungary under the Hungarian monarch. Although Croatia remained linked with Hungary for eight centuries, the Croats were sometimes able to choose their rulers independently of Budapest. In personal union with Hungary, Croatia retained its own diet and was governed by a ban, or viceroy. After the battle of Mohács in 1526 most of Croatia came under Turkish rule. In 1527 the Croatian feudal lords agreed to accept the Hapsburgs as their kings in return for common defense and retention of their privileges. During the following century Croatia served as a Hapsburg outpost in the defense of central Europe from a Turkish onslaught.

The centralizing and Germanizing tendencies of the Hapsburgs, however, severely weakened the power of the Croatian nobility and awakened a national consciousness. During the 19th cent. Hungary imposed Magyarization on Croatia and promulgated (1848) laws that seriously jeopardized Croatian autonomy within the Hapsburg empire. Joseph Jellachich, ban of Croatia, had the diet pass its own revolutionary laws, including the abolition of serfdom. Jellachich's forces also marched against the Hungarian revolutionaries in the 1848-49 uprisings in the Hapsburg empire. When the dual Austro-Hungarian monarchy was established in 1867, Croatia proper and Slavonia were included in the kingdom of Hungary, and Dalmatia and Istria in the Austrian empire. The following year Croatia, united with Slavonia, became an autonomous Hungarian crownland governed by a ban responsible to the Croatian diet.

Despite the achievement of autonomy in local affairs, Croatia remained restless because of continuing Magyarization. Cultural and political Croat and South Slav organizations arose, notably the Croatian Peasant party, founded in the early 20th cent. With the collapse of Austria-Hungary (1918), the Kingdom of Serbs, Croats, and Slovenes (later renamed Yugoslavia) was formed. Serbs dominated the new state, however, and promoted centralization, ignoring Croat desires for a federal structure.

Agitation resulted in the assassination (1928) of Stepjan Radić, head of the Croatian Peasant party. After Radič's successor, Vladimir Maček, connived with fascist Italy to form a separate Croatian state, Yugoslavia allowed the formation (1939) of an autonomous banovina comprising Croatia, Dalmatia, and parts of Bosnia and Herzegovina. Nevertheless, many Croats, especially members of the Ustachi fascist terrorist organization, insisted on complete independence.

When the Germans invaded Yugoslavia in 1941, the Ustachi seized power and declared Croatian independence under Ante Pavelič. Croatia was placed under Italian and later German military control, while the Ustachi dictatorship perpetuated brutal excesses, including the establishment of concentration camps; in the Croat-operated Jasenovac camp alone, it has been estimated that some 200,000 Serbs, Jews, Romani (Gypsies), and Croat opposition figures were killed. A large part of the population joined the anti-Fascist Yugoslav partisan forces under Tito, himself a native of Croatia.

Pavelič fled in the wake of Germany's defeat in 1945, and Croatia became one of the six republics of reconstituted Yugoslavia. Croatian nationalism persisted in Communist Yugoslavia, however, and the Ustachi and other émigré nationalist groups remained active abroad. A major Yugoslavian decentralization reform that took effect in the early 1970s was designed in part to satisfy Croat demands for increased autonomy and dampen secessionist sentiment. The death of Tito in 1980, however, weakened Yugoslavia and increased demands for secession.

In 1990, the Croats elected a non-Communist government and began to demand greater autonomy. On June 25, 1991, Croatia declared its independence, with Franjo Tudjman, a former general, as president. Immediately fighting erupted with federal troops (mostly Serb) and Serbs from the predominantly Serb-populated areas of Croatia. The Serbs carved out the Republic of Serbian Krajina in central and NE Croatia.

In Jan., 1992, after other European Community-brokered cease-fires had failed, a more stable truce was mediated by the United Nations, which in February sent in a peacekeeping force. This force froze the territorial status quo, which left 30% of the land, in Serb hands and also left as refugees many Croatians who had been displaced by "ethnic cleansing" from Serb-held lands. Croatia was recognized as an independent nation by the European Community (now the European Union) in Jan., 1992, and was accepted into the United Nations. In 1993, Croatian forces launched attacks against Serb rebels in various areas. During 1995, Croatian forces recaptured most Serb-held territory (but not E Slavonia, in the northeast), leading approximately 300,000 Serbs to flee into Bosnia and Yugoslavia; in war crime trials in 2010, Croatian forces were accused of deliberately expelling many Serb civilians in the campaign.

Croatia had supported and directed Bosnian Croats when fighting erupted in neighboring Bosnia in 1992, and Croatia played a role in negotiations for a Bosnian peace agreement. The Bosnian peace treaty was signed by Croatia, Bosnia, and Serbia in Dec., 1995. A separate accord called for the return of E Slavonia to Croatian rule; this went into effect in Jan., 1998, following a transition period overseen by UN peacekeeping forces. The international community has expressed concern over Croatia's slow implementation of the Bosnian peace treaty, the delay in the return of Serb refugees, and alleged human-rights abuses, including the muzzling of independent newspapers. Tudjman's autocratic rule and failure to cooperate on Bosnian issues led to Croatia's international isolation in the late 1990s.

In Nov., 1999, Vlatko Pavletic, the speaker of parliament, became acting president as Tudjman lay on his deathbed. Parliamentary elections in Jan., 2000, resulted in a victory for a six-party, center-left opposition coalition, and, after a runoff in February, Stjepan (Stipe) Mesić, an opposition candidate, captured the presidency. Elected on a reform platform, the coalition failed to improve Croatia's stagnant economic situation, and in the Nov., 2003, parliamentary elections the conservative nationalist party founded by Tudjman won a plurality of the seats. The party, the Croatian Democratic Union (HDZ), formed a minority government the following month, with Ivo Sanader as prime minister.

Mesić was reelected in Jan., 2005, after a runoff in which he defeated Deputy Prime Minister Jandraka Kosor. In Oct., 2005, the European Union opened membership talks with Croatia, contingent on Croatian cooperation with the war crimes tribunal for the former Yugoslavia. Croatia's claim to large areas of the Adriatic, effectively blocking Slovenia's maritime access from its coast, and other issues have created tension between the two nations. In Aug., 2007, however, the countries agreed to submit their boundary disputes to the International Court of Justice. The HDZ again won a plurality in the Nov., 2007, parliamentary elections; Sanader remained prime minister, leading a coalition government.

Croatia began excluding EU members from a protected fishing zone off its coast in Jan., 2008, despite a previous agreement with the EU. The act threatened to delay accession talks with the EU, but enforcement of the zone was suspended in March. However, negotiations with the EU were slowed nonetheless, as Slovenia blocked some talks because of its border dispute. In Apr., 2009, Croatia joined NATO; the Slovenian border dispute had threatened to postpone Croatia's accession.

In July, 2009, Sanader announced his resignation as prime minister; Jadranka Kosor succeeded him, becoming Croatia's first woman prime minister. Slovenia ended the freeze on Croatia's accession talks after Croatia agreed in September that none of the documents associated with its EU application would have any legal impact on the resolution of the border dispute. Ivo Josipović, the candidate of the opposition Social Democrats, was elected president in Jan., 2010.

In Dec., 2010, Sanader was arrested on an international warrant in Austria after Croatian prosecutors sought to detain him in connection with a corruption investigation. He was extradited to Croatia in July, 2011, and additional corruption charges were brought against Sanader (and the HDZ itself) at the end of the year; Sanader was convicted of taking bribes and in 2012. Parliamentary elections in Dec., 2011, resulted in a majority for the center-left Kukuriku coalition led by the Social Democrats and Zoran Milanović. Later the same month the country signed a treaty with the EU that was intended to lead to its accession as a member in mid-2013; a referendum (Jan., 2012) approved joining the EU, but turnout within Croatia was only 47%.