The Indian government has launched one of the country's most ambitious efforts to tackle rural poverty.
The scheme will target India's 60m rural households
Under the National Rural Guarantee Scheme one member from each of India's 60 million rural households is guaranteed 100 days of work each year.
They will receive a minimum wage of 60 rupees ($1.35) or an unemployment allowance if there is no work.
More than a third of India's population of more than one billion people lives on less than $1 a day.
The first phase of the programme will cover 200 of the country's poorest and least developed districts.
The BBC's Navdip Dhariwal, who is in southern Andhra Pradesh state, says this is a demonstration of the government's resolve in bringing a new deal to rural India.
Hundreds of thousands of villagers have been lining up in all 200 districts hoping to benefit from the scheme.
Prime Minister Manmohan Singh launched the scheme in a village in the drought-prone Anantapur district of Andhra Pradesh by handing out job cards to five villagers.
"We must tirelessly work to ensure that the benefit of the scheme reaches needy people," the Press Trust of India quotes him as saying.
"The main focus of the scheme is the poorest of the poor."
The president of the governing Congress Party, Sonia Gandhi, was also present and described the programme as "an important and a revolutionary step".
But she added: " Howsoever noble a scheme is... it will be of no use if it's not implemented with transparency and accountability."
The Congress Party swept to power in 2004 after it pledged to improve the conditions of India's poor.
The programme will be extended to the entire country over the next four years and is being seen as an important effort to curb the migration of villagers to India's overcrowded cities.
The Congress campaign used the scheme in election campaigns
Analysts say this is the most ambitious pro-poor scheme launched by an Indian government, in a country where nearly 70% of the population lives in villages.
"It is the biggest social security net ever provided in India," the country's Rural Development Minister, Raghuvansh Prasad Singh, told the BBC.
People employed by the scheme will work on projects such as building roads, improving rural infrastructure, constructing canals or working on water conservation schemes.
The government says special priority will be given to women.
However, critics say the scheme is too expensive and question whether the government has the funds for a programme expected to cost anywhere between $5bn-25bn.
They say rather than paying for unskilled manual labour, the government should invest in improving rural infrastructure - especially in health care and education.
Others say there is little transparency, which may lead to red tape and corruption.