The weather was bitterly cold last January, but the fashions inside The Fashion Centre at Pentagon City near Washington, D.C., were hot. Too hot, thought Dianne Purvis, a 48-year-old secretary for NASA, as she watched her daughter, 12, and niece, 13, coo over a skimpy top. "That's too old for you," she told them. "It's nothing!" they insisted. "It's not nothing to me," Purvis replied as they exited the store. And so goes the latest battle in the wardrobe wars. At retail meccas like Guess and Express, young girls 12 to 19 are spending $37 billion a year on clothes such as belly-baring shirts and micro miniskirts. Your preteen may be one of them, as one room recently discovered when she found three skimpy thongs hidden in her daughter's backpack.

The trick for mothers, experts say, is to help daughters understand the subtle and overt messages these outfits telegraph, then draw the line between school clothes, party wear and what's outright unacceptable. That's no easy task in a world of bump-and-grind videos and sexually charged TV shows. Many morns can't find age-appropriate clothes on the racks. But retailers claim they sell what customers want. "Like their target audience, teen-market retailers take their cues from what's popular in magazines and music videos and on TV," says Ellen Tolley, a spokesperson for the National Retail Federation in Washington, D.C. It's up to parents, she says, to dictate what's appropriate.