Liberia was founded in 1821, when officials of the American Colonization Society were granted possession of Cape Mesurado by local De chiefs for the settlement of freed American slaves. African-American immigrants were landed in 1822, the first of some 15,000 to settle in Liberia. The survival of the colony during its early years was due primarily to the work of Jehudi Ashmun, one of the society's agents. In 1847, primarily due to British pressures, the colony was declared an independent republic. The Americo-Liberian minority controlled the country's politics, and new immigration virtually came to an end with the American Civil War. Liberia was involved in efforts to end the W African slave trade.

Attempts to modernize the economy led to a rising foreign debt in 1871, which the republic had serious difficulty repaying. The debt problem and constitutional issues led to the overthrow of the government in 1871. Conflicts over territorial claims resulted in the loss of large areas of land to Britain and France in 1885, 1892, and 1919. However, rivalries between the Europeans colonizing West Africa and the interest of the United States helped preserve Liberian independence during this period. Nevertheless, the decline of Liberia's exports and its inability to pay its debts resulted in a large measure of foreign interference.

In 1909 the government was bankrupt, and a series of international loans were floated. Firestone leased large areas for rubber production in 1926. In 1930 scandals broke out over the exportation of forced labor from Liberia, and a League of Nations investigation upheld the charges that slave trading had gone on with the connivance of the government. President C. B. D. King and his associates resigned, and international control of the republic was proposed. Under the leadership of presidents Edwin Barclay (1930-44) and William V. S. Tubman (1944-71), however, Liberia avoided such control.

Under Tubman, new policies to open the country to international investment and to allow the indigenous peoples a greater say in Liberian affairs were undertaken. The country's mineral wealth, particularly iron ore, began to be exploited, and there was a gradual improvement of roads, schools, and health standards. Upon Tubman's death in 1971, Vice President W. R. Tolbert took charge, and in 1972 he was elected to the presidency. Although Tolbert cultivated a democratic climate and favorable relations abroad, an organized opposition emerged early in his regime, some of it from Liberian students living in the United States. In 1979, a government proposal to increase the price of rice produced widespread violence.

In 1980, Tolbert was assassinated in a coup led by Master Sergeant Samuel K. Doe. Pledging a return to civilian rule in 1981, the government unleashed a campaign to subdue opposition. In 1984 the military government instituted a series of constitutional reforms that included shortening the presidential term and outlawing the formation of a one-party state. Doe became Liberia's first indigenous president (by a fraudulent election) in 1985. The Doe government was infamous for corruption and human-rights abuses; it also became the target of numerous coup attempts. Thousands of refugees fled to Guinea and Côte d'Ivoire during this period.

Late in 1989, Liberia was invaded from Côte d'Ivoire by rebel forces of the National Patriotic Front of Liberia (NPFL), led by Charles Taylor, who proclaimed himself president. The United States sent troops to the area when the NPFL threatened to take foreign hostages. Doe was assassinated in 1990 by another group of rebels led by Prince Yormie Johnson, who also sought the presidency. The Economic Community of West African States (ECOWAS) intervened to negotiate a peace settlement among the two rebel groups and the government. ECOWAS also sent a Nigerian-led West African peacekeeping force to Monrovia and installed an interim government led by Amos Sawyer. Taylor's forces, with military aid from Libya and Burkina Faso, began a siege of Monrovia in 1992 and engaged in fighting with ECOWAS forces.

A number of cease-fires were established in 1993 and 1994, but clashes between factions persisted. In Aug., 1995, a new peace accord was signed in Abuja, Nigeria, that provided for an interim government headed by Wilton Sankawulo, with national elections to be held late in 1996. In Apr., 1996, fierce factional fighting resumed in the capital; however, disarmament was begun later that year, and the war formally came to an end in 1997. It is estimated that between 150,000 and 200,000 lives were lost in the civil strife, with hundreds of thousands of refugees having fled the country.

Multiparty presidential and legislative elections held in July, 1997, brought Charles Taylor to power. Under Taylor, the country remained economically devastated while he and his family enriched themselves by looting Liberia's resources. In the late 1990s, Liberia was accused of supplying troops to support rebel forces in Sierra Leone's civil war. Taylor, a long-time ally of the Revolutionary United Front (RUF) in Sierra Leone, had supplied the rebels with arms in exchange for diamonds. In 2000 the United Nations placed an 18-month ban on the international sale of the diamonds in an attempted to undermine the RUF, and in May of the following year it also imposed sanctions on Liberia. In mid-2001 fighting erupted in N Liberia between anti-Taylor rebels and government forces. The fighting intensified during the following year, and the rebels continued to expand the war into other regions of Liberia in 2003; that year the United Nations also placed an arms embargo (2003-9, modified in 2006 to allow the equipping of the military and police) on Liberia. By mid-2003 the rebels controlled roughly two thirds of the country and were threatening to seize Monrovia, leading to calls for Taylor to step down and for the United States, as a nation with historical ties to Liberia, to send peacekeeping forces.

In August, Taylor resigned and went into exile; he was succeeded temporarily by his vice president, Moses Blah. A peace agreement was signed with the two rebel groups, and several thousand West African peacekeepers, supported temporarily by an offshore U.S. force, arrived. In Oct., 2003, the West African force was placed under UN command and was reinforced with troops from other nations; businessman Gyude Bryant became president of a new power-sharing government.

Despite the accord with the rebels, fighting initially continued in parts of the country; tensions among the factions in the national unity government also threatened the peace. By the end of 2004, however, more than 100,000 Liberian fighters had been disarmed, the former government and rebel forces had agreed not to rearm, and the disarmament program was ended. In June, 2004, a program to reintegrate the fighters into society began, but the funds proved inadequate by year's end. In light of the progress made President Bryant requested an end to the UN embargo on Liberian diamonds and timber, but the Security Council postponed such a move until the peace was more secure. Bryant's government was hindered by corruption and a lack of authority in much of Liberia, but the peace enabled to the economy recover somewhat in 2004.

In the presidential election in the fall of 2004 former soccer star George Weah won the first round with 28% of the vote, but lost the runoff in November to Ellen Johnson Sirleaf, a politician and former World Bank official who received nearly 60% of the second round votes. Weah charged that the runoff had been rigged, leading to street protests. Most observers regarded the election as having been free and fair, and Weah subseqently dropped his challenge of the vote. Sirleaf became the first woman to be elected president of an African nation. At the same time a new national legislature was also elected, with no party securing a controlling position.

Sirleaf, under international pressure, requested in Mar., 2006, that Nigeria extradite Charles Taylor, who was then brought before an international tribunal in Sierra Leone to face war crimes charges arising from events during the Sierra Leone civil war (his trial was later transferred to The Hague for security purposes; he was convicted of war crimes in 2012). In June, 2006, the United Nations ended its embargo on Liberian timber, but continued its diamond embargo until an effective certificate of origin program was established; the diamond embargo was finally lifted in Apr., 2007.

In Mar., 2007, former interim president Bryant was arrested and charged with having embezzled government funds while in office. The Liberian Truth and Reconciliation Commission, which had conducted a four-year investigation of the nation's civil strife, issued its report in July, 2009; it recommended that the president (who at originally supported Charles Taylor) and many other senior politicians be banned from politics for 30 years. In the 2011 presidential election, Sirleaf was reelected after Winston Tubman, her opponent in the November runoff, withdrew and called for a boycott. He asserted that the poll was rigged, but his claim was not backed by foreign observers or the supreme court, and the third place finisher had thrown his support to Sirleaf. Government corruption remains a significant problem in Liberia.