Her first reaction was: "Yikes!"
Her father's business had done better than she knew - a lot better. She got more money than she ever expected. Much more than she needed, CBS News correspondent Richard Schlesinger reports.
"It's so unsettling when you have so much and somebody else is struggling," Liebman said.
She knew she wanted to give most of it away. But did she know how to go about giving away millions of dollars?
"No," she said.
Anne and Christopher Ellinger run an organization called Bolder Giving mostly for people like Becky Liebman: The suddenly super rich who want to give away large sums.
"So many people, even people who are really committed to giving, are giving just a fraction of their capacity," Anne Ellinger explained.
Philanthropists believe if everyone who gives would donate just 1 percent more it would mean an extra $100 billion a year in contributions.
One hundred billion a year?
"A year! It's not just saying once," Ellinger said. "It's saying year after year after year."
The Ellingers inherited roughly one million dollars and gave half of it away, to places like an arts center for troubled kids.
"If somebody asks us are we nuts to have given away so much money, I think to myself, we would have been nuts to just buy more stuff," Christopher Ellinger said.
More than 80 people have joined Bolder Giving around the country. They're not all super rich, but they are all very generous. So far the amount they have given adds up to about $1 billion.
Becky Liebman has helped endow this youth center near where she lives and she's spending much more on a list of projects around the country.
"Many millions of dollars have come into my life," she said. "Many millions of dollars have gone out."
She's still looking for other causes - working hard at her role as accidental philanthropist. She measures her worth not by how much money she's gotten, but by how much she's given.