They may not be of age to drink legally. Some aren't even old enough to drive a car. But when it comes to banking millions, these folks are already pros. Hollywood's 10 top-earning tweens collectively pulled down $107 million between June 1, 2007 and June 1, 2008. Though many of the stars on Forbes' list have already aged out of the 8-to-14-year-old demographic themselves, the bulk of their work still caters to that advertiser-beloved tween set. According to Alloy Media and Marketing, it's a rabid and often indulgent fan base: America's 20 million kids aged 8 to 12 spend $51 billion of their own money annually and influence $150 billion more in spending by their doting parents.
Tied for the top spot: Hannah Montana star Miley Cyrus and Harry Potter lead Daniel Radcliffe. The young talents each banked a cool $25 million in the last year. At just 15 years old, Cyrus is the face of a billion-dollar brand. Her TV series proves a ratings stalwart for the Disney channel, and everything from lunch boxes to backpacks bear her face. What's more, her sold-out Best of Both Worlds 70-date concert tour raked in $54 million, and the 3-D concert movie brought in nearly $70 million more. Next up: a Hannah Montana flick for the big screen. Though Cyrus' saccharine-sweet image was temporarily tested when she posed for a Vanity Fair shoot in what appeared to be only a bed sheet, her cult-like fan base remained loyal. Proof: in its first week, her recently released, solo debut album Breakout sold some 371,000 copies. Its chart-topping success makes Cyrus the youngest star ever to have three No. 1 albums in a two-year span. Radcliffe similarly tapped into the tween zeitgeist, thanks to his role as boy wizard Harry Potter in Warner Brothers' $4.5 billion film franchise. Last summer, the British-born star signed a contract worth an estimated $50 million to continue his leading role in the last two Potter installations. The final story, Harry Potter and the Deathly Hallows, has since been split into two movies, which could mean even more cash for the 19-year-old star. When he isn't mixing potions, Radcliffe is doing his best to broaden his range--and his audience. He recently played the title role in My Boy Jack, a television movie about Rudyard Kipling's ill-fated son. Next, he'll make his Broadway debut in a revival of Peter Shaffer's play Equus. Radcliffe's earlier rendition, a stage play in London's West End, drew tremendous media attention when the young star appeared nude. Tabloid staples Mary-Kate and Ashley Olsen place third on the list, banking an estimated $15 million over the course of the year. Though the 22-year-old starlets are no longer in the tween demographic, their tween-focused retail empire, Dualstar (which they assumed control of when they turned 18) continues to find buyers. Now the fashion-forward twins, still best known for their shared role as precocious tot Michelle Tanner on ABC's Full House, are trying to attract an older audience with two adult-focused fashion lines, the Row and Elizabeth & James. Another set of siblings takes the no. 4 spot with earnings of $12 million. They are tween sensation the Jonas Brothers. After a rocky start--the New Jersey-reared brothers were dropped by their Sony (nyse: SNE - news - people ) recording label--the clean-cut trio has proved they have enduring star power. Their franchise has already raked in upwards of $50 million from touring, album sales and merchandise. When it comes to the Jonas Brothers, that's only the beginning. In March, the brothers signed a multimillion-dollar, 140-show contract with concert promoter Live Nation (nyse: LYV - news - people ). They kicked off their Burning Up tour in July and have a new CD, A Little Bit Longer, set for release this month. They also have a Disney channel series, titled J.O.N.A.S. (for Junior Operatives Networking As Spies) in the works, and a 3-D concert film coming to movie theaters in 2009. Rounding out the top five is High School Musical star Zac Efron, who raked in $5.8 million in the last year. Thanks to his success in the lucrative Disney franchise as well as last year's summer blockbuster Hairspray, the 20-year-old heartthrob has scored parts in a slew of upcoming flicks. Among them: the Big-esque comedy Seventeen Again, indie biopic Me and Orson Welles and Disney's highly anticipated silver-screen feature High School Musical 3.
No. 10: Vanessa Anne Hudgens $3.2 Million
Surviving the buzz from some indiscreet Web pictures, Hudgens, 18, is back in High School Musical 3. She's released a new album and has become a face for Neutrogena skin products and Marc Ecko sneakers.
No. 9: Rupert Grint $5 Million
The red-headed Brit, 19, is making an estimated $5 million playing Ronald Weasley in Harry Potter and the Half-Blood Prince. He's spent some of his fortune on his childhood dream: an ice cream truck.
No. 8: Hilary Duff $5 Million
Before Miley Cyrus, Disney phenom Hilary Duff owned the tween market. Now the former Lizzie McGuire star, 20, is striving for a more mature audience with roles in indie flicks Greta, Safety Class and War, Inc.
No. 7: Emma Watson $5.5 Million
The English sweetheart, 18, will once again play girl wizard Hermione Granger, in Harry Potter and the Half-Blood Prince. Her estimated paycheck: $5 million. Last year, she starred in Ballet Shoes, a BBC TV movie.
No. 6: Ashley Tisdale $5.5 Million
Tisdale, 23, heads to the big screen as Vanessa Hudgens' foil in High School Musical 3. She also does voice work for the Disney Channel's animated Phineas and Ferb and endorses Red by Marc Ecko.
No. 5: Zac Efron $5.8 Million
The High School Musical star and tween heartthrob, 20, had success last summer in Hairspray. Three upcoming movies: Seventeen Again (a comedy), Me and Orson Welles (an indie) and this fall's highly anticipated High School Musical 3.
No. 4: Jonas Brothers $12 Million
In the past year, these tween rockers, ages 15 to 20, pulled in $9 million from touring, plus another $3 million from CD sales, merchandise and television deals. In the works: a movie, a reality series and a TV drama.
No. 3: Mary-Kate And Ashley Olsen $15 Million
They're 22 now, but the pint-sized twins still learn most of their income from their tween-oriented clothing and accessories outfit, Dualstar. They're also designing two lines for adults, the Row and Elizabeth & James.
No. 1 (Tie): Miley Cyrus $25 Million
Cyrus' 70-date Best of Both Worlds concert tour sold out faster than you could say "Hannah Montana," leaving legions of screaming girls scrambling for tickets. In the past year, the 15-year-old also sold millions of CDs, signed a book deal and began filming a movie based on her Disney Channel series. She'll soon lend her voice to an animated canine comedy, Bolt.
No. 1 (Tie): Daniel Radcliffe $25 Million
Last summer the British-born boy wizard, 19, signed a jaw-dropping contract worth an estimated $50 million to continue his leading role in the last two parts of the Harry Potter series. The final story, Harry Potter and the Deathly Hallows, has since been split into two movies, which should mean even more cash for him. Radcliffe also played the title role in BBC's TV movie My Boy Jack, a World War I story about Rudyard Kipling's ill-fated son, and he'll be baring all on Broadway in Equus.