ABC News' Linsey Davis and Matt Knox report:

Young girls are growing up faster than ever before, wearing makeup and high heels. But what about a cosmetic treatment that many middle-aged women find painful?

More teens and tweens today want to get waxed, a grooming technique that involves applying hot wax to remove unwanted body hair.

And a new ad for a salon chain that offers discounts on waxing for girls 15 and younger has reinvigorated the debate among parents about how young is too young.

"To encourage it at such a young age is completely inappropriate and disgusting," a New York City woman said after seeing the ad, which features a girl who appears to be under the age of 15 jumping in the air in a bikini.

"It turns my stomach," another added.

The debate erupted after a 50 percent-off promotion began running for Uni K Wax salons up and down the East Coast, targeting teens 15 and younger to celebrate their independence this summer by getting waxed.

"Celebrate Freedom and Independence All July," the ad reads. "During the month of July, girls 15 and under can enjoy their FIRST waxing experience and find it NATURAL, SAFE and PLEASANT."

It's not just this ad. It seems many teens and tweens - some as young as 10 - are now prepping for summer camp by removing unwanted hair.

Anna Dolgon-Krutolow, 12, begged her mother to take her to Uni K Wax Salon in New York City for a bikini wax. "I swim when I'm at camp so I just wanted to just be fresh," she said.

For her mother, Carol Dolgon-Krutolow, the procedure wasn't an easy sell.

"She was very adamant, you know, and she's becoming a woman," her mom said. "She's very concerned about how she looks and it's important that I listen to her."

But some, including Atlanta-based therapist Tiffanie Henry, fear that waxing could be over-sexualizing teen girls. "I just really have a difficult time stomaching, inviting girls, specifically girls who are 15 years of age and younger into a salon to be waxed," said Henry, co-host of ABC's "The Revolution."

Uni K Wax stands by its promotion. In a statement to ABC News, the CEO and founder Noemi Grupenmager said the promotion is intended to help young girls boost their self esteem.

"By the age of 11 or 12, some young girls develop hair on their legs and upper lip. This can not only be embarrassing, but it often makes these young girls targets for bullying at school, especially during PE and recess," Grupenmager said. "Uni K Wax is offering a safe solution in a comfortable environment for these girls."

This was the case for Anna, who considers the procedure a confidence booster and said she plans to come back for another wax.

"I really feel that once I go to camp I'm going to be more self confident and less self conscious, which is a really great feeling," she said.

Uni K Wax requires minors younger than 17 to have their parents sign a consent form before receiving any treatments.

Therapist Henry advises that tween waxing opens the door even earlier for mothers to have an important conversation with their daughters about their bodies.

"Moms need to be talking to their daughters about grooming, about their daughter's body changing, about hair growing in places that hair has never grown before," Henry explained.

Click here to read the full statement as received by ABC News from Noemi Grupenmager CEO and founder of Uni K Wax Center.