Jaws dropped when she emerged from the dressing room wearing a sheer black sheath with a single strap.
"You look absolutely fabulous," her mother said, then gasped, after eyeing the stunning head-turner.
"She did look good in it ... but it wasn't age appropriate," recalled Diane Goldie, who nixed the purchase for her 12-year-old daughter, Grace.
Billions of dollars are on the line in the fashion industry which targets the 8-to-12 set known as tweens. But it's a line increasingly blurred between cute and hot, adorable and sexual.
In addition to spending $30 billion of their own money, American tweens hold sway over another $150 billion spent by their parents each year. It was just about a decade ago that the marketing and advertising industries popularized the phrase "tween" to sell 8- to 12-year-olds everything from entertainment to clothing.
"You go into a juniors department, you have a rack of clothing that is appropriate for an 11-year-old next to a rack of clothing that isn't," said Alex Morris, who recently reported on tweens and fashion for New York magazine. "It's certainly blurring the lines. ... It's making it harder for parents to set boundaries."
New research released by The American Psychological Association earlier this year found that sexual imagery aimed at younger girls is harmful to them and increases the likelihood they will "experience body dissatisfaction, depression and lower self-esteem."
The entertainment industry isn't making it any easier. A few years ago, Miley Cyrus played the sweet Hannah Montana on the Disney Channel. Now she's in black leather hot pants. She's 17. Other teen stars have done similar things. Britney Spears' bubblegum pop image morphed into provocateur. Ashley Tisdale went from "High School Musical" to "Cranking It Up." And Nickelodeon's Amanda Bynes is now on the cover of Maxim.
"The easiest way for a celebrity to transition from being a child star to an adult star is the pathway through their sexuality," said Morris. "Children are attracted to this kind of look, it's what they see Mylie Cyrus wearing, Demi Lovato wearing, Lindsay Lohan wearing."
It's also what Gossip Girl's Taylor Momsen is wearing on the pink carpet as the face of Material Girl, the newly unveiled clothing line created by Madonna and her 14-year-old daughter Lourdes. Critics say the line is perfect for a woman in her 20s but far too racy for girls in elementary or middle school.
Trampy Tween Fashion or a Return to Modesty?
Says Momsen, "It's very much about putting you own look together to be yourself."
While searching for their own look, tweens are strongly influenced by the celebrities they idolize. Grace, whose image is "something edgy, but also looks high fashion, like urban chic," was on a shopping spree when she grabbed a chunky sweater that exuded that aura. "It's the one on the Glamour cover! Like what Taylor Swift was wearing!" she exclaimed.
Some fashion watchers say the pendulum is swinging back, away from trashy 12 and closer to sweet 16.
"I think we are having a return to modesty," said Ann Shoket, editor of Seventeen magazine, the oracle of fashion for teens and the tweens who follow them in lock step.
"The girls that (teens and tweens) are looking up to, Miranda Cosgrove ("iCarly"), Victoria Justice ("Victorious"), Selena Gomez ("Wizards of Waverly Place"), these are teen stars that are good girls. You would never see them behaving badly or rolling out of a club," said Shoket.
Madonna and Diane Goldie agree it's a mother's responsibility to guide a young daughter to make the right choices.
"I don't have to be her friend. I'm her parent," said Goldie. "We can be friends when (she is) 30, but for now we do have the back and forth."
Madonna told ABC News that a mother's job is to "say 'no!'" She added, "I'm very strict about the way my daughter dresses. We have arguments about how short the skirt is ... is there cleavage?"
Lourdes said she pushes the envelope, knowing her mother won't hesitate to push back. "I mean obviously I don't agree with all of her decisions. I know it's coming. But I might as well try and see what happens."
Seventeen's Shoket says that attitude is only natural for girls in a crucial stage of development. Said Shoket, "They are starting to develop their own sense of personality, and what feels right and it's about pushing boundaries."