Bolivian President Evo Morales has signed a law convening a special assembly to rewrite the constitution.
Mr Morales called on Bolivians to take part in the country's reforms
Mr Morales said Bolivia would be refounded, with indigenous peoples playing the role that they had been denied for hundreds of years.
Mr Morales also signed a law calling a referendum on greater regional autonomy, which will be held on 2 July.
He was elected in December 2005, pledging to reform the constitution and give more power to indigenous peoples.
The assembly is expected to spend up to a year drawing up a new constitution before it is put to a referendum.
The 255-strong group, which will have a quota of women members, is also scheduled to be elected on 2 July.
Sessions are to be held in the city of Sucre.
Correspondents say the document is likely to increase indigenous rights and state control of the Bolivian economy.
Mr Morales has said the free-market model does not work in Bolivia, and the partial privatisation of basic services and natural resources should be reversed.
He called on Bolivians to take part in the country's reforms.
The July referendum is aimed at decentralising power in Bolivia. In the past, governors were appointed by the president, not by popular vote.