Liberia owes its establishment to the American Colonization Society, founded in 1816 to resettle freed American slaves in Africa (see Slavery). An attempt at colonization in Sierra Leone had failed in 1815. Six years later native rulers granted a tract of land on Cape Mesurado, at the mouth of the Saint Paul River, to U.S. representatives, and the first Americo-Liberians, led by Jehudi Ashmun, began the settlement. In 1824 an American agent for the society, Ralph Randolph Gurley, named the new colony Liberia and the Cape Mesurado settlement Monrovia. Other separate settlements were established along the coast during the next 20 years. Soon, however, conflicts arose between the settlers and the society in the United States. By the time Joseph Jenkins Roberts became the first black governor in 1841, the decision had been made to give the colonists almost full control of the government. A constitution modeled on that of the United States was drawn up, and Liberia became an independent republic in July 1847. Roberts was its first president, serving until 1856. Liberia was recognized by Britain in 1848, by France in 1852, and by the United States in 1862.

In the beginning of the 19th century the tide started to rise in favour of the abolition of slavery, and the Grain Coast was suggested as a suitable home for freed American slaves. In 1818 two U.S. government agents and two officers of the American Colonization Society (founded 1816) visited the Grain Coast. After abortive attempts to establish settlements there, an agreement was signed in 1821 between the officers of the society and local African chiefs granting the society possession of Cape Mesurado. The first American freed slaves landed in 1822 on Providence Island at the mouth of the Mesurado River. They were followed shortly by Jehudi Ashmun, a white American, who became the real founder of Liberia. By the time Ashmun left in 1828 the territory had a government, a digest of laws for the settlers, and the beginnings of profitable foreign commerce. Other settlements were started along the St. John River, at Greenville, and at Harper. In 1839 Thomas Buchanan was appointed the first governor. On his death in 1841 he was succeeded by Joseph Jenkins Roberts, a black man born free in Virginia in 1809; Roberts enlarged the boundaries of the territory and improved economic conditions.

In December 1989 a group of dissidents began an uprising against the government. The National Patriotic Front of Liberia (NPFL), a rebel group led by Charles Taylor, soon had an ill-trained army of 10,000 men, and within weeks they controlled much of the countryside. A split among the insurgents only increased the violence as fighting continued into 1990. An Economic Community of West African States (ECOWAS) monitoring group (ECOMOG) was sent to Liberia as a peacekeeping force, but failed to halt the fighting. Doe was captured and executed by a splinter group of the NPFL in September 1990. The destruction of Liberia’s economy begun by Doe was completed by the war.