But analysts noted that the 41 percent voter turnout was the lowest since Chile's return to democracy, suggesting she'll need to move deliberately, not radically, when she begins her second turn in office next year.
"The social and political conditions are here and at last the moment has arrived," Bachelet said after winning 62 percent of the vote in a runoff against the center-right's candidate, Evelyn Matthei.
"If I'm here it's because we believe that a Chile for everyone is necessary," Bachelet added. "It won't be easy, but when has it been easy to change the world?"
Bachelet then planned to meet with congressional party leaders who will be key to approving her $15 billion program to overhaul education, improve health care and reduce the vast gap between rich and poor.
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The moderate socialist ended her 2006-10 presidency with 84 percent approval ratings despite failing to achieve any major changes. This time, Chilean leftists vow to take over the streets again if the politicians don't follow through.
Matthei's 37 percent was the center-right's worst performance in two decades, and yet Jovino Novoa, vice-president of the right-wing Democratic Independent Union, asserted today that Bachelet "doesn't have the representation nor the mandate for extreme positions."
The center-right Renovation National's president, Carlos Larrain, was more accepting, saying "Michelle Bachelet is the president of Chile and she's been elected with a very solid majority."
"She'll achieve some things: The tax reform is in her pocket. ... I think student leaders who have been elected to Congress will sign off on educational reform. Bachelet's expectations are high, but things will be achieved," said Kenneth Bunker, a Chilean political scientist.