Judy Blume jumps into her Jeep, backs out of her covered driveway and flies along the broad, color-saturated streets of the sumptuous southernmost tip of the United States known as Key West, Fla. She can't be late.

"You will not believe where this class takes place," she says, although there are clues as she maneuvers along the backside of a drab strip mall. Out she leaps, a bundle of energy in a neon yellow T-shirt, black stretch pants, white bobby socks and black heels, rushing through a dank-smelling gym into the mirrored back room. The music starts.

Ladies and gentlemen: We bring you Judy Blume, tap dancer.

"Ball change, step, dig, spank, ball change!" shouts instructor Bruce Moore, a colorful Key West fixture who doesn't particularly care that one among his flock is an iconic children's book author.

"Oops, I screwed up," Blume says timidly, looking his way. On her next try, the class, seven other mostly grandmothers, breaks into applause. Blume buries her face in her hands and laughs like the schoolgirl she still is, in so many ways.

If it's jolting to accept that Judy Blume is 70, an even bigger stunner is this: Margaret -- sweet, soul-searching, breast-challenged Margaret -- would be nearly 40. But, dear God, does age really matter? Because, while Blume's best-known character couldn't have imagined a world of text-messaging and Nintendo DS, her story of growing up, of friends won and lost, of desperately seeking acceptance (and, sometimes, a training bra) is timeless.

This is probably why Blume, the name on more than 80 million copies of 25 books, from the charming "The One in the Middle Is the Green Kangaroo" to the goofy Fudge books to the naughty "Wifey" for grown-up girls, can step out and then step right back in, as she is doing with a new four-book series. The books, for ages 5 to 8, feature the everysiblings Abigail and Jake introduced in her original picture book, "The Pain & The Great One."

"After writing 'Summer Sisters' [in 1998], I said, 'I'm never doing this again.' It was the hardest book I ever wrote," says Blume, relaxing in the spacious contemporary home that she and her husband, George Cooper, live in eight months of the year. When the book about friendship and class conflict was done, 20 drafts later, Blume panicked. She told Cooper they needed to get the manuscript back. People would hate it.

The book became a bestseller, but Blume still felt spent.

A few years later, though, her 10-year-old grandson, Elliot, began to nudge her to write another Fudge book, for him (the first few were inspired by her son, Larry). "Double Fudge" came out in 2002, and writing was fun again. A few failed movie deals left Blume convinced to do more projects like Fudge, "where I didn't have to worry about what Hollywood would think." She signed a four-book contract for "Pain" before writing a word. "Whoa!" she exclaims. "But I needed that pressure, the momentum, to be writing again."

Coming out of her shell

Judy Sussman grew up in a Jewish home in Elizabeth, N.J., with a homemaker mother and dentist father which, she jokes, explains why teeth are an issue in so many of her books. Her brother, David, was four years older. "I was very shy, quiet, anxious," she recalls. She was also very attached to her father. "My father was fun," she said. "Everybody loved him. He was a Toastmaster for dental events. He taught me about classical music." Her mother was more guarded, more complex. "Life is harder for some people than others," she says.

When Judy was in third grade, the Sussmans made an abrupt move to Miami Beach, to give David a warm respite for a childhood ailment. They lived with her maternal grandmother for two years while her father flew down on weekends. "As much as I missed my father, I loved it there," says Blume, still lovely and not much larger than her childhood self, all curly red hair and cheekbones. "I played outside until dark. I was coming out of my shell. When I got back to New Jersey, I was a changed person, much more social."

And mischievous. In sixth grade, she started writing book reports about the horse tale "Dobbin Rides Again." But there was no such book. When she speaks to classrooms now, she encourages teachers to let kids make up a book report -- once.

At home, she was mischievous, too, grabbing J.D. Salinger and Ayn Rand from her parents' bookshelves. "I wasn't reading 'The Fountainhead' for Rand's philosophy," she says. "There was sex in it!" She turned 12 in 1950 and describes playing Spin the Bottle in fine Judy Blume form:

"I spent two minutes in the closet with Pat Flannery. He said he was going to kiss me. I said, 'On my lips?' He said, 'Yeah, where else would I kiss you?' "

Although the high school seniors in her groundbreaking and controversial "Forever" have sex (protected and with a trip to Planned Parenthood), Blume herself was cautious. "The three smartest, most popular girls were pregnant at graduation," she says of her class. "The last girls you'd ever think would do it."

"Soon, though, her life took a dramatic turn. At 21, while a junior at New York University, her father died of a heart attack while she held his hand. He was just 54. Grieving and confused, she married her college sweetheart, John Blume, earned a degree in education and had two children in rapid succession. The marriage quickly soured. She developed allergies and felt all wrong for suburban life in Scotch Plains, N.J.

Blume started writing as a way to stay sane. "The One in the Middle Is the Green Kangaroo" was published in 1969, a happy tale of a triumphant middle child. Things got edgier from there. In 1970, her "Are You There God? It's Me, Margaret" gave voice to pubescent girls everywhere. It is rare to find a woman age 12 to 40 who hasn't read "Margaret," which is why so many of us howled at E! comedian Chelsea Handler's new book title, "Are You There, Vodka? It's Me, Chelsea." (Blume, for the record, had never heard of Handler.)

After Margaret came "Iggie's House," which tackled bigotry. Then "It's Not the End of the World," about divorce; "Blubber," a chilling tale of cruelty directed toward an overweight girl, and "Forever," which one critic called a "sexual how-to book for junior high school students." "Wifey," Blume's first adult novel, delved into the complexities of long-term marriage, and explored STDs and swinging. From 1982 to 1996, Blume ranked No. 1 on People for the American Way's cumulative Most Challenged Authors list, ahead of Salinger, John Steinbeck and Mark Twain. That propelled her into lifelong activism against censorship.

Not everyone's a fan

Blume is well aware that she has critics aside from the censors. Some readers dislike her insistence on ambivalent endings. But that's the way life is, Blume says. Others find her writing less than literary. "Story is not my strong point," she responds. "Character is my strong point. When I started to write, I vowed I would never write books that kids would do book reports on. I wanted them reading me on window seats, under the covers with flashlights."

Mission accomplished. "Tales of a Fourth Grade Nothing," and the Fudge books to follow remain timeless 30 years after they were written because Blume knows kids like nobody's business. She knows how frustrating siblings and clueless parents can be, how awful it feels to be on the outside looking in. Blume knows how to make kids laugh and feel OK about themselves.

"I don't think she's ever lost, with the passage of time, the sense of how kids interact with each other, siblings and adults," says Beverly Horowitz, Blume's publisher and editor for 20 years. "She's respectful of the intelligence of kids, and honest about the ups and downs of relationships."

She knows those ups and downs well. Her 16-year marriage to John ended in 1975. She quickly remarried, which she says was a disaster for her kids. The marriage lasted just four years. The only happy part was that she landed in Santa Fe, N.M. And when Cooper, a former law professor, came to visit his young daughter, his ex-wife suggested that he take out her friend Judy. The couple went out on two dates before he moved in with her. "It was the '70s," Blume says. "We were all crazy."

They've been together for 28 years, married for 21. Cooper, also 70, is trim and handsome and a calming antidote to his wife, who confesses to being "a little neurotic." He is also a Key West celebrity of sorts, having raised capital to transform a dilapidated warehouse into the Tropic Cinema, a stunning Art Deco movie theater.

Little wonder the Blume-Coopers love this city they've called home for 13 years. (They own places in New York City and Martha's Vineyard, too.) The two begin most days with a 2-mile walk before Blume heads into her studio to write. She rides her bike to the grocery store; they've been vegetarians for nearly 30 years and she jokes that their wine tastes run from "red to white to Manischewitz."

Blume is working the phones on behalf of Barack Obama, in addition to doing book events and school appearances. Recently, a 10-year-old boy approached Blume at his school and confessed his love for her. "I love you, too," she said sweetly. "I want to marry you," he told her. She told him that was a lovely thought, but she already was married. "Then get divorced," he said.

She laughs in the recounting, out of delight and, no doubt, relief. Her third marriage is a charm. Her children are grown and doing well. Daughter Randy, 47, is a clinical social worker and her grandson, Elliot, is now a handsome 16. Blume has collaborated on media projects with her son, Larry, 44, a film producer. Cooper's daughter, Amanda, 40, lives in New Mexico with her husband and runs Democratic political campaigns.

Blume, who was awarded the National Book Foundation's Medal for Distinguished Contribution to American Letters four years ago, says other authors are fighting the censorship battle now. That gives her more time for politics, tap dancing and updating her website (www.judyblume.com). And meeting the deadline for that fourth book.

"It's so exciting every single time," says Blume, channeling her inner girl. "Bringing out the latest two books, I thought, Yes!"

Gail Rosenblum • 612-673-7350