Dilma Rousseff has been sworn in as Brazil's first female president, pledging to build on the policies of her hugely popular predecessor and mentor Luiz Inacio Lula da Silva.
Mr Lula's 63-year-old former cabinet chief, assumed the presidency in Brazil's Congress on Saturday after a short motorcade ride during which she waved to an estimated 70,000 well-wishers lining Brasilia's streets.
The daughter of a Bulgarian immigrant, Ms Rousseff is a former Marxist guerrilla who was jailed and tortured during a military dictatorship in the 1970s.
She was elected in October, defeating opposition candidate Jose Serra by 56% to 44% in a run-off vote.
After swearing an oath and signing official documents before lawmakers in Brazil's Congress, she gave her first speech to the nation as president, AFP reports.
She swore she would protect the most vulnerable in Brazil's society and "govern for all".
Ms Roussef repeatedly paid homage to Mr Lula, saying she had been honoured to serve under "the great man" and pledged to maintain his achievements, notably in reducing poverty and promoting economic prosperity.
"The most determined struggle will be to eradicate extreme poverty," she said. "We can be a more developed and fairer country."
Ms Rousseff outlined plans for tax reforms, environmental protection, improved health services, regional development - and unspecified measures to combat foreign "speculation" that could upset Brazil's economic growth.
Ms Rousseff is taking over a country with an economy that grew an enviable 7.6% in 2010, enjoys recently discovered oil finds that could make it a big-league exporter, has won a significant role on the world stage, and is preparing to host the 2014 football World Cup and 2016 Olympics.
Mr Lula was required to step down after serving the maximum two consecutive terms permitted under Brazil's constitution.
