More than a month of violent protests over the Bolivian Government's plans to export natural gas have brought down President Gonzalo Sanchez de Lozada.
BBC News Online's Latin America analyst Robert Plummer explains what has caused the crisis.
Why is gas so important to Bolivia?
Bolivia is one of the poorest countries in the Americas but has Latin America's second-biggest reserves of natural gas. Exporting the gas to the US and Mexico as President Sanchez de Lozada's government planned could make the difference between boom and bust.
Economists say that since Bolivia has an annual trade deficit of between $300m and $500m, the gas export plan is the only way the country can balance its books.
The plan also has the backing of the International Monetary Fund which believes it could increase Bolivia's growth rate by a whole percentage point over the next five years.
So why the protests?
Mainly because macro-economic arguments like these cut no ice with Bolivia's impoverished indigenous Indian majority, who feel that the economy is run for the benefit of a wealthy elite.
Bolivia has been a democracy since 1982 after decades of political instability and repeated military coups. But during that time, inequalities of wealth have increased and there has been no reduction in poverty.
As a result, ingrained Latin American hostility to giving up control over natural resources has now combined with the Bolivian masses' wider sense of economic exclusion to produce a socially explosive mixture.
Nationalism also plays a key role. The idea of selling off Bolivia's gas to the US was always certain to anger the president's left-wing opponents, fearful of being exploited by the "gringos" to the north.
Bolivian pride was further dented by the idea of exporting the gas by way of a Chilean port - an outlet that was in fact part of Bolivian territory until Chile seized Bolivia's coastline in their 1879-83 war.
What have the protesters been demanding?
As far as Bolivia's gas reserves are concerned, the protesters are calling for them to be nationalised and made available exclusively to the Bolivian people.
They are unconvinced by economists who say that it would take no more than 1% of Bolivia's reserves to satisfy the country's entire market in gas.
Other demands include higher wages, better pensions, comprehensive land reform and Bolivia's withdrawal from the planned Free Trade Area of the Americas.
Among the most militant of the protesters are coca-growing peasants in the central Chapare region, who have been radicalised by US-backed attempts to eradicate their crop as part of Washington's "war on drugs".
Why did the president resign?
President Sanchez de Lozada was arguably slow to respond to the sheer ferocity of the protests, making concessions only after it emerged that dozens of people had been killed.
The US-educated president, who spent most of his early years in exile, was ill-suited to the task of reaching out to his political opponents.
They became determined to push their campaign for indigenous rights all the way to the presidential palace.
Goni, as the president is nicknamed, won the August 2002 election with just 22.5% of the vote, and remained deeply unpopular.