Girls Gone Mild

Christina Aguilera, 26 — Getty Images/Peter Kramer

Like Britney Spears, Christina Aguilera got her big break on "The Mickey Mouse Club," but their adult lives have been very different. Sure, Aguilera went through her "Dirrty" phase of raunchy videos, but she never seemed to lose control in her personal life. She's now happily married and is rumored to be expecting.

This photo shows Aguilera at a Nylon magazine party on March 21, 2007, in New York.

Hayden Panattiere, 17

The "Heroes" star began her career in commercials at only 11 months old. She gained recognition for her work as Lizzie Spaulding in "The Guiding Light" and is now the cheerleader Claire on "Heroes."

Panattiere is one of many young stars who aren't partying themselves into oblivion. Click to read about more of Hollywood's good girls.

Hilary Duff, 19

Like Britney Spears, Hilary Duff got her start on kids' television, starring in the popular Nickelodeon series "Lizzie Maguire." But she's managed to keep her squeaky clean image, even when she was dating a rock star (Joel Madden of Good Charlotte.)

Here, Hilary arrives at the 2007 Much Music Awards in Toronto on June 17, 2007.

Keira Knightley, 22

4) Metallic Fabric — Getty Images/Dave Hogan

Gorgeous "Pirates of the Caribbean" star Keira Knightley landed her first TV role at age 7 after pestering her actor parents to let her join the family business. She has said she has no desire to live in Hollywood and makes her home in London.

Knightley is shown here at a party for the European premiere of "Pirates Of The Caribbean: Dead Man's Chest" on July 3, 2006 in London.

Amanda Bynes, 21

"I think I'll go out as much as I've ever gone out ... which is not a lot," actress Amanda Bynes told E's Ted Casablanca just after turning 21. Bynes showed her flair for goofy sketch comedy on Nickelodeon's "The Amanda Show" and currently stars as uptight Penny Pingleton in the new movie "Hairspray."

Bynes is shown here at the New York premiere of the film "Hairspray" on Monday July, 16, 2007.

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Natalie Portman, 26

Portman made her film debut in 1994, and later shot to stardom in 1999 in "Star Wars: Episode I -- The Phantom Menace." She took time off from her acting career to get a college degree from Harvard and speaks Hebrew, French and Japanese in addition to English.

Portman keeps it simple at the 2007 Vanity Fair Oscar Party at Mortons in this Feb. 25, 2007 photo.

Nicky Hilton, 23

Aside from a quickie marriage to a man 12 years her senior that was later annulled, Nicky Hilton is not nearly as scandal-prone as her big sister, Paris. She's been designing handbags since she was a teenager and has her own clothing line, Chick by Nicky Hilton.

Nicky Hilton is shown here arriving at the Gwen Stefani concert at the Palms Casino Resort in Las Vegas on April 21, 2007.

Miley Cyrus, 14

She's got a hit show, "Hannah Montana," on the Disney channel and her first album debuted at No. 1 earlier this month. But, she still has to do her chores and her homework, and she goes to church with her family on Sunday. Hopefully, as she grows up she'll stay grounded.

Actresses Miley Cyrus appears onstage during MTV's "Total Request Live," Tuesday, June 20, 2006, in New York.

Scarlett Johansson, 22

Actress and style icon Scarlett Johansson once told London's Observer that her only vice is Swiss cheese. She has dated a few high profile celebrities, but tends to keep her personal life private.

Johansson is shown here at the premiere of "The Black Dahlia" at the 63rd Venice Film Festival on Aug. 30, 2006.

Mandy Moore, 23

Mandy Moore emerged as a teen pop princess in 1999 with her platinum album "So Real," but her acting career has far overshadowed her career as a singer. She's dated a string of celebrities such as Wilmer Valderrama and Zach Braff, but she's stayed scandal free.

Mandy is shown here arriving at the premiere of Warner Bros. Pictures' "License to Wed" at the Cinerama Dome Theater on June 25, 2007, in Los Angeles.

America Ferrera, 23

As the title character in "Ugly Betty," America Ferrera shows that real beauty is on the inside. She sees her character as a positive role model for young Latinas. She is one semester shy of earning her bachelor's degree at USC and is dating a fellow student there.

Ferrera is shown here arriving at the 13th Annual Screen Actors Guild Awards on Sunday, Jan. 28, 2007, in Los Angeles.

Jo Jo, 16

Although she's only 16, actress and singer Joanna "Jo Jo" Levesque has the poise of someone much older. Her 2004 hit "Leave (Get Out)" earned her a place is the youngest solo artist to have a No. 1 hit on the top 40 mainstream chart. She and teen soccer star Freddy Adu ended their year and a half relationship last fall.

Jo Jo arrives at the premiere of "RV" on April 23, 2006, in Los Angeles.

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Carrie Underwood, 24

Aside from dating football player Tony Romo, Carrie Underwood has kept a relatively low profile in her personal life. The award-winning country singer and former "American Idol" was recently named the world's sexiest vegetarian by PETA.

In this photo, Underwood arrives to the "American Idol Season 6 Finale" on May 23, 2007, in Hollywood, Calif.