The new First Lady made her White House speaking debut Thursday for a cause and celebration close to her heart.

Michelle Obama warmly welcomed an overjoyed crowd invited to the White House for her husband’s first bill-signing – a law designed to assure equal pay for women.

“As I told guests, feel free, walk around, touch some stuff,” an inviting Obama said to laughter as she welcomed the 150 or so guests, including Secretary of State Clinton, in the White House’s State Dining Room.

“Just don’t break anything. It’s what I try to tell my kids.”

The “don’t break anything” line was a reprise of President Obama’s gentle reminder last week to a visiting group.

Thursday’s gathering came hours after the President signed the Lilly Ledbetter Fair Pay Act, named after the Alabama granny who took her pay dispute against the Goodyear Tire Co. all the way to the Supreme Court.

The court ruled in 2007 that Ledbetter had no case because she had failed to file her claim within 180 days of her employer’s decision to pay her less than a man doing the same work (leaving unclear how she was supposed to know that).

The new law tosses out that narrow time limit.

The First Lady, who got to know Ledbetter on the campaign trail, lauded her for showing courage and called her “an inspiration to women and men all across the country” in a short-but-sweet, three-minute speech.

“She knew unfairness when she saw it and was willing to do something about it because it was the right thing to do, plain and simple,” the First Lady said as guests sipped orange juice and noshed on apricot coffee cake, orange scones, apple muffins and fruit salad.

Displaying her own lawyerly credentials, Michelle Obama added, “This legislation is an important step forward, particularly at a time when so many families are facing economic insecurity and instability.”

President Obama worked the crowd, too, but had to skip out before his wife – stylishly dressed in a businesslike purple suit, white pearls and matching purple pumps – took to the lectern. Earlier, he offered his own praise for Ledbetter, who spent 19 years working for Goodyear.

“Lilly Ledbetter did not set out to be a trailblazer or a household name. She was just a good hard worker who did her job – and she did it well – for nearly two decades before discovering that for years, she was paid less than her male colleagues for doing the very same work,” Obama said as Ledbetter looked on.

Later, Ledbetter returned the favor with some heartfelt thanks to the Obamas and their decision to put equal pay for women at the top of the administration’s legislative to-do list.

“Goodyear will never have to pay me what it cheated me out of. I will never see a cent from my case. But with the passage and the President’s signature today, I have an even richer reward,” Ledbetter said to applause and a hug from the First Lady.

“I know that my daughter and granddaughters, and your daughters and your granddaughters, will have a better deal,” added Ledbetter. “That’s what makes this fight worth fighting.”