Princess Mia Thermopolis will don her tiara for the last time in Forever Princess, the 10th and crowning installment of Meg Cabot’s Princess Diaries series. Turned down by 12 houses before finding a home in 1999, the inaugural novel, The Princess Diaries, launched one of the first commercial, girl-oriented series that have been so successful in the young adult market during the last decade.

The Princess Diaries, released in 2000 by HarperCollins, and its sequels have been published in 38 countries and have sold more than five million copies in the U.S. alone. HarperTeen plans a 75,000-copy first printing for Forever Princess, out in January, in which Mia writes a historical romance, agonizes about selecting a college, celebrates her 18th birthday at a celebrity-studded bash and graduates from high school.

Cabot originally envisioned Princess Diaries as a novel for adults, basing its premise on an incident from her own life. “After my father died, my mom started going out with one of my former teachers,” she says. “I was 30 at the time, but you’re never too old to be grossed out by a parent, and I started writing a story about a 30-year-old whose mother dates her daughter’s former teacher.”

When Cabot showed the story to friends, they suggested she make her protagonist younger, which sparked the idea of writing the novel as the diary of a 14-year-old who is mortified by her mother’s dating behavior. “I knew that something more had to happen—maybe she should be kidnapped by aliens or turn out to be a princess,” recalls the author, who concluded that the princess bit “was a little more realistic.”

Cabot says she balked when her agent, Laura Langlie, advised her that Princess Diaries was more appropriate for a teen audience. “I though it was a crazy idea, but Laura was adamant,” she recalls. The manuscript grabbed the attention of Abby McAden, then an assistant editor at Avon Books for Young Readers, who signed it up. Shortly thereafter, HarperCollins’s parent company, News Corporation, acquired Hearst Book Group, which included Avon, and Princess Diaries was released under the HarperCollins imprint.

Meg Cabot.
Photo: Ali Smith.

“I had been in publishing less than two years,” McAden says. “I wasn’t jaded in any way and wasn’t hampered by any noise about whether it would work or not.” Now paperback publishing director at Scholastic, McAden edits Cabot’s Allie Finkle’s Rules for Girls and Airhead series for that house.

“Meg kind of caught the wave when the market opened up to commercial young adult fiction, which had previously been driven more by library sales and reviews,” says Langlie, noting that The Princess Diaries sold 40,000 copies in hardcover even before the release of the 2001 Disney movie based on the book. The agent believes that the Princess Diaries series and Louise Rennison’s Confessions of Georgia Nicholson series “really created” the chick lit genre (“though I don’t like that phrase,” she adds) for teen readers.

Zareen Jaffery, senior editor at HarperCollins Children’s Books, edited Forever Princess after arriving at the house last January. She praises Cabot’s ability “to create characters, like Mia, who readers can entirely relate to, characters that they’d like to be friends with.”

“She’s a princess, but she has boy problems, friendship problems, school problems and parent problems,” says the author. “I get so many e-mails from readers saying, ‘Mia’s just like me, except for the princess part.’ I saved all my diaries from growing up, so these novels are filled with real life stuff—with a little tiara on top, which makes them fun to write and fun to read.”

The author had always planned to end the Princess Diaries story arc when Mia graduated high school. “I knew I wanted her to turn 18 and finish high school, but I didn’t want to follow her to college,” she says. “I keep thinking of things that would be great for her next story, and then I have to remind myself that there will be no next one. It has taken a lot of adjustment.”

A “tiara” designed by makeup artist Bobbi Brown, for the online auction.

But Cabot has no shortage of other writing projects. Due from Scholastic next spring are Best Friends and Drama Queens, the third installment of Allie Finkle’s Rules for Girls; and Being Nikki, the second Airheads title. Cabot, who also pens the Heather Wells Mysteries series for adults, comments that she “may start a new adult series—if I can find the time.”

As a lighthearted, metafictional tie-in, Ransom My Heart, the medieval romance written by Mia in the final Princess Diaries book,will be published by Avon in January. (The cover notes that the novel is written by the princess, “with help from Meg Cabot.”) Cabot actually wrote the book some time ago, but she never thought it would sell. “I couldn’t believe it when Avon decided to publish it,” she says. In Forever Princess, Mia sells her romance to Avon—and donates her author proceeds to Greenpeace, and Cabot is doing the same in real life.

Mia will get a royal sendoff on January 9, when Cabot will give a talk about Forever Princess and sign copies of the book at an evening event at the New York Public Library in midtown Manhattan. On display will be a selection of the tiaras designed by 25 celebrities—among them Julie Andrews, Judy Blume, Tommy Hilfiger and Princess Marie-Chantal of Greece—which will be auctioned online during the month of January. Proceeds will benefit programs for teens at the NYPL’s 87 branches.

Forever Princess by Meg Cabot. HarperTeen, $16.99 ISBN 978-0-06-123292-3