A decade ago, a plucky, unabashedly moody heroine first appeared in the pages of Megan McDonald’s Judy Moody, an early chapter book from Candlewick. Readers were smitten by Judy’s moods and meanderings, prompting the author to pen eight subsequent novels starring this character, plus three featuring her and her spunky brother Stink, two activity books, and a journal—all illustrated by Peter H. Reynolds. The series is now available in 24 languages, has won more than 30 awards, and has a worldwide in-print tally of 12 million copies. And its publisher is staging a Judy Moody’s 10th-birthday celebration that’s now in full swing.

This spring Candlewick reissued all of the Judy Moody books to mark the occasion, with a new cover design and added content, including an interview with the heroine, samples from the activity books, and teasers to other titles. The publisher has also revamped its dedicated Web site, and has added to the series’ offerings. Judy Mood’s Way Wacky Uber Awesome Book of More Fun Stuff to Do, a paperback activity book, was released in January; and Stink: Solar System Superhero, a hardcover chronicling the boy’s mission to reinstate Pluto as a planet. And Judy returns in August—this time solving a mystery—in Judy Moody, Girl Detective, which will have a 150,000-copy first printing.

To celebrate Judy’s milestone and tout the new titles and series’ redesign, McDonald has embarked on a 10-city tour, which will take her to New York City for BEA and to Toronto—her last stop—in the fall. She is grateful for her character’s popularity and longevity—if a bit surprised. “Who would have thought it?,” she says with a laugh. “It’s amazing to me, since when I wrote Judy Moody I thought it was just a single book. It wasn’t conceived of as a series, but grew in a kind of grassroots way, with my readers wanting more of her.”

Musing on why Judy Moody has resonated so deeply and widely with fans, McDonald mentions her heroine’s flaws, which are easy to relate to. “She has bad moods, sometimes gets in trouble, and not everything always goes right for her, and kids can connect to all of that in a very real way.”

Readers also meet Judy at an impressionable age, McDonald notes. “I think there is something significant about those first chapter books we read,” she says. “They are the first books that kids tackle as independent readers, and that is a huge accomplishment for them. I still remember how strongly I felt about Beverly Cleary’s books when I read them in the third grade or so—and about Louise Fitzhugh’s Harriet the Spy.”

A highlight of the 10th birthday commemoration was last Saturday’s Judy Moody Day celebration in McDonald’s hometown of Sebastopol, Calif., which drew a crowd of several hundred. The event featured arts and craft activities, kids’ yoga demonstrations, and a treasure hunt. And Screamin’ Mimi’s Ice Cream shop, which Judy, Stink, and pals frequent in the series’ novels, featured two special flavors for the day—Gold Rush and German Chocolate Cake—concoctions invented by the winner of a Judy Moody contest run by the store.

McDonald, who called Saturday’s extravaganza “an amazing event with a huge turnout,” cites two particular high points of the day. “Probably the most touching thing for me was to meet a whole bunch of high-school girls who came clutching their old, tattered copies of Judy Moody books—some of which I’d signed in 2001,” she says. “They told me that these were their favorite novels in third grade—and that they still love and read Judy.”

Also gratifying to the author was the chance to meet—and introduce to the crowd—Oliver Kneen, a runner-up in Candlewick’s Judy Moody Ultimate Fan Sweepstakes. “His entire family had flown in from Houston for the event, which was amazing,” McDonald says. “I was so impressed! We gave him a set of autographed books.” The sweepstakes winner (selected at random from entrants who correctly completed a Judy Moody trivia quiz) is a girl from San Diego who will have a character named after her in a mini mystery included in Judy Moody, Girl Detective.

Judy will make her silver-screen debut next year—ideally on April 1, her birthday—when Smokewood Entertainment is slated to release a film with the working title of Judy Moody and the NOT Bummer Summer. McDonald collaborated on the screenplay with Kathy Waugh, a friend and screenwriter. Candlewick will issue at least two movie tie-ins next spring: a paperback novelization and a hardcover entitled Judy Moody Goes Hollywood, which takes Judy and gang behind-the-scenes on the movie set.

Judy Moody fans will be happy to hear that McDonald is now working on a new, still untitled novel in which the protagonist, fed up with all the bad news in the paper, creates her own newspaper that McDonald says, “features just good moods and good news.” And her brother will be back soon in Stink and the Ultimate Thumb Wrestling Smackdown, revealing what the resourceful boy does when his parents insist he play a sport.

Beyond that, the author looks forward to following these siblings’ subsequent adventures into the next decade. And does she expect there will be a 20th anniversary celebration in her future? “I certainly hope so,” replies the author.