Author! Author!

Once upon a time, books by multiple authors got no respect. Sure, these teams proudly displayed their names on nonfiction titles and genre fiction such as the hugely popular "Left Behind" biblical series by recent Newsweek cover dudes Tim LaHaye and Jerry B. Jenkins. But when it came to traditional fiction, coauthors did the literary equivalent of hiding under a stone: They would publish under a pseudonym or use only one author's name.

Such arrangements had bad reputations in the industry.

"Dual authors have been notorious for being unable to work together to produce anything," says Molly Stern, senior editor at Viking Penguin, "or they work so well, any individuality is rubbed off the text [leaving it] without any personality."

Then came 2002's "The Nanny Diaries." Emma McLaughlin and Nicola Kraus's novelized version of their experiences as nannies on New York's Upper East Side broke all preconceived notions about coauthored books. It sold almost 1.4 million copies in hard-cover and paperback. Miramax is trying to adapt the book for screen and television. The fruits of their success can be seen on the shelves of local bookstores: Now you can't escape the bevy of novels by more than one writer.

This spring brought the releases of "The Rule of Four" by Ian Caldwell and Dustin Thomason, "The Second Assistant: A Tale From the Bottom of the Hollywood Ladder" by Clare Naylor and Mimi Hare, and "The Right Address" by Carrie Karasyov and Jill Kargman.

"A Love Story" by husband-and-wife team Denene Millner and Nick Chiles comes out next month. McLaughlin and Kraus's second novel, "Citizen Girl," arrives in November. And next year "The Vow" will up the ante by juggling the voices of three writers: Angela Burt-Murray, Mitzi Miller, and Millner.

What makes these unions work are age-old friendships; most have written together (or at least known one another) for years. They trade on a literary style that gets richer with each anecdote. Each set of coauthors may write in different ways, but they all agree that one element makes their partnerships work: blunt honesty. The result is prose strong enough to boost some of these novels onto bestseller lists. Hard work? Sure. But the word these writers use most to describe their cooperative writing experiences is "fun."

"I mean, the beauty of Mimi and I writing together," says Naylor, a British fiction writer with three novels under her belt, "is you always have someone else not just to bounce ideas off of but who cares as much about something as you do. It's very hard to get someone else to listen -- boyfriend, family, anybody -- when you're working on something yourself. There's really only so much dedication you can expect from other people. You can expect peak commitment from your writing partner. It's sort of like a lovely kind of marriage."

Twice the experiences Can these writers overcome the problems that once doomed this kind of work to failure? People magazine gave "The Right Address" a three-star review, but the critic griped: "The plot is predictable. The dialogue is often awkward. And . . . they could have dug deeper." Stern doesn't speak only for herself when she says, "I can say with great certainty that a work of literature would never be coauthored."

Stern's reservations didn't stop her from acquiring "The Second Assistant" when it crossed her path, lured by its exuberance and how it fit into the hot gossip/chick lit categories. The 32-year-old authors put into fiction form what Naylor calls the "brilliant and ridiculous" Hollywood stories they'd heard during their seven years writing screenplays together. Hare, whose sister Kristina is the wife of nightclub owner Patrick Lyons, had even more tales to offer from her experiences on the sets of Oliver Stone's "Heaven and Earth" and "JFK." She gathered anecdotes as she climbed the executive ranks at the Ladd Company and Gracie Films production houses, working on "Jerry Maguire" and "As Good As It Gets."

Karasyov and Kargman have written screenplays since 1998, and it was as a screenplay that "The Right Address" first came into being. Like Naylor and Hare, they found inspiration in their own experiences -- growing up on the Upper East Side as the daughter of the president of Chanel (Kargman) and the daughter of the founder of auctioneer Doyle New York (Karasyov). Kargman, 29, thinks the novel thrives because it offers two perspectives. "There's definitely more textures and layers than there could have been with one writer," she says. "There are more stories, more snubs, more hilarious encounters. I just think it makes for a richer stew."

Coauthoring also makes sense to Millner, who's written three novels with her husband since they got their start in 1999 with a nonfiction relationship book. Now she's writing and editing "The Vow" with Miller and Burt-Murray on the heels of the release of their spring nonfiction title "The Angry Black Woman's Guide to Life." "The Vow" weaves the stories of three Hollywood girlfriends -- a rising star, a movie agent, and an entertainment journalist -- who agree to find husbands in the next year. Miller takes care of the rising star's chapters, Burt-Murray the agent's, and Millner the journalist's.

"Terry McMillan in her last book ["A Day Late and a Dollar Short"] had six different characters," says Millner, 35. "She had to write those six different characters in six different voices. I don't think that's all that easy to do. If you have a great story and your girl has a set of experiences and you have another set of experiences [and] the two of you come together, I think it makes it a little bit easier to do that."

Friends and writers It's no coincidence that most of these partnerships grow out of friendships. The authors of "The Rule of Four" told Publishers Weekly that they've known each other since they were 8 years old. Karasyov and Kargman went to the Spence School together. Both had careers in the magazine world before joining forces to write screenplays. Their first was the 2000 indie film "Intern"; they now have a two-picture deal at Paramount.

The Hare/Naylor relationship began seven years ago when Naylor was in Hollywood pitching a screenplay to Hare. They immediately clicked. Hare told Naylor she wanted to write. Naylor encouraged her to do so. A few months later, Hare quit her job at Gracie Films and unexpectedly showed up in London.

"I said, `Oh my God, what are we going to do with this person?' " says Naylor, teasing Hare, who's listening nearby. "I don't know her. I don't know where she's going to stay. I thought, I've got other things to do than playing around on some screenplay with some girl I don't know." Now with Uma Thurman set to star in their romantic comedy "The Accidental Husband," with Wayne Wang directing, Naylor says, "I don't know what it would have been like without her."

These teams swear they don't suffer from creative stasis. For them, there's nothing more inspiring than a partner. "When someone else's livelihood depends on it," says Karasyov, 32, "it really kicks your butt to get up in the morning and sit down at the computer. We both have small children. We both still write for magazines. It would be very easy to say, `Oh, we're just going to do our magazine work and take care of our kids.' But we are ambitious and did want to do this."

In fact, having a second (or third) set of eyes peruse the prose can only heighten its quality, says Suzanne Gluck, cohead of William Morris Agency's literary department. She represents the coauthors McLaughlin and Kraus, and Tonya Lewis Lee (director Spike's wife) and Crystal McCreary Anthony, whose first effort -- a satire about rich African-Americans called "Gotham Diaries" -- will be released in July. "What I see," says Gluck, "is a lot better because I'm sure that their partner edited out what I shouldn't have seen."

Millner says friendly competition with her husband helped her reach a higher level of creativity when the demands of a full-time job and a family wore her out. "I'd sit down and write my stuff and I just felt weak. `My prose is wack. Ugh, I haven't grown at all.' . . . So I was forced to figure out -- very quickly -- how to step up my game."

In the Chiles-Millner household, each chapter of their novel is written from the perspective of either the main male character or the main female one. As a self-proclaimed procrastinator, Millner writes around the chapters her husband has already produced. She doesn't get that leeway as she writes and edits chapters of "The Vow" with Miller and Burt-Murray.

Working styles Every partnership works differently. On "The Second Assistant," experienced novelist Naylor took the lead, while Hare rewrote their screenplay "The Accidental Husband." Hare would write a chapter and then Naylor would go over it so each chapter had the same voice. Even Hare's nuptials last year didn't stop the process. "We'd call and discuss stories while she was on honeymoon, which wasn't very popular," says Naylor.

They worked separately, says Naylor, "sitting at our desks to midnight in different parts of London kind of slogging and eating and not really moving, and not really having any friends anymore." They were on the phone with each other every 15 minutes, says Hare. "We had huge phone bills doing it that way. `OK, we're going to put the phone down and do 1,000 words. Call me back when you're done.' So we'd put the phone down. `OK, I've done 922 words.' . . . We found that if we did end up in the same room we'd wind up gossiping, giggling, and [doing] silly things that aren't necessarily productive -- shopping."

Naylor, whose fourth novel, "The Goddess Rules," comes out next year, found it tough to relinquish the control she has as a solo author. "Having to debate different things with someone else -- not necessarily easy, but I think it builds someone's character," she says, laughing. "It makes me a little more reasonable. I mean, novelists can become incredibly difficult."

Since "The Right Address" is an accidental novel, Karasyov and Kargman had different issues. They wrote the original version together in the same room as a spec script inspired by the success of "The Devil Wears Prada" and "The Nanny Diaries," which were getting film deals. After reading the duo's screenplay, however, their agent told them that while it was a good read, it explored too rarefied a world.

"I beg to differ," says Kargman, "but the reason we chose to novelize it is that `The Devil Wears Prada' and these books set in this world have garnered these huge option fees for movies. [Our agent] said . . . those were novels first. They had a built-in following by the time they were on the block for movie sales."

Since Karasyov lives in Santa Monica, Calif., and Kargman in New York, the Internet became their best friend as they adapted the screenplay into a novel. Karasyov would write a chapter, then send it to Kargman, who would read it and make changes. Chapters flew back and forth. "It's become so layered," says Karasyov, "there's really not one chapter that's solely Carrie's or solely Jill's. Even with different lines it could be either one of us."

The teams overcome dullness and other problems with bluntness.

"The gloves are off," says Millner. "If it [stinks] you hear it. . . . With Angela and Mitzi we're extremely [honest] . . . but it's very necessary. In order for the book to work, you have to have three well-oiled parts working together."

That attention to quality is helping coauthors find a new level of success. "The Right Address" was No. 27 on last week's New York Times bestseller list, right behind James Patterson and Andrew Gross's "3rd Degree." These days, Stern, the Viking Penguin editor, says, "I would be willing to venture that there's a new receptivity to it. If someone sent me a literary novel by two people, it would be genuinely acceptable."

Karasyov and Kargman are already at work on their sophomore effort. Unlike the authors of "The Nanny Diaries," who refused to write "The Nanny Diaries 2," then watched Random House pass on their workplace satire "Citizen Girl," Karasyov and Kargman won't stray far from their original subject matter.

"This time you'll hear more from the younger set," says Kargman. "But not much more."