Most of her contemporaries may have traded in their tube tops for corporate uniforms, but Britney Spears is still looking very much like Britney Spearswhich, for a woman of 21, is a little alarming. Even with 50 million records sold, Spears should be quaking in her candy pink, jewel-encrusted Skechers right about now. With her ex-boyfriend Justin Timberlake riding the success of a hit solo album and touring this summer with Christina Aguilera, teen pop seems to be having a more sophisticated second comingwithout her. After a somewhat narrow evolution across three albumsfrom corruptible schoolgirl to dazed, wholesome Southern stripper, and with a glimmer of something edgier and more expansive on her third effort, BritneySpears has no choice but to push past the middle ground she sang about in her last hit single, the growing-pains ballad Not a Girl, Not Yet a Woman.

But in a quadruplex apartment on Lafayette Street in downtown Manhattana dozen flights up from a sea of NYU undergrads, many of whom helped drive the teen-pop phenomenon of the late ninetiesBritney Spears is her not-so-old familiar self: the iconic girl-woman, sprightly and almost frighteningly perfect looking (more so in person than on TV), with blooming skin and big, sparkling eyes buried somewhere under a jailbait smear of dark mascara. Shes decked out in classic Britney-wear: a dramatically cropped black-and-white striped halter top and, below seven golden inches of midriff, baggy black pants held up by black and pink suspenders. Theres an oversize white Patricia Field baseball cap on her head and a long rhinestone pendant hanging from her navel. (She does not, like a few of her rivals for Billboard domination, go in for Fred Leighton bling bling.)

Dont be fooled, though: The new Britney is currently being forged at a studio in the Flower Districtand thats where Spears has been all day, hard at work on her fourth album. This whole album has been a huge experiment for me, she says, settling into a lawn chaise on her terracethen falling right through to the floor as the cushion gives way. Rental, she notes with a laugh that shes never afraid to direct at herself. Everyone Id go work with, they have this perception, this vision of me, and a lot of times Im like, ugh! It took me a while to figure out the right vibe and find producers who really got me. Im nervous. Im excited, but whoa!

Recording artists feel a constant pressure to maintain what the folks at Spearss label, Jive Records, call Q-factor: the burst of commercial heat at the outset of a singers career. No one has had more Q-factor than Spears, but she seems to understand, young as she is, that pop stars age in dog years and that shell need some new tricks if she wishes to snatch her crown back from the 18-year-old Canadian anti-Britney, Avril Lavigne. I f---in love Avrils stuff, Spears insists. It f---in rocks. But she goes on to reveal a touch of competitiveness. Avril doesnt really dance, but whatever. Its weird. My third album sold as much as her first one, which is very funny to me because everyone thought it didnt do that great. Its clear, in any case, that Spearss new record, which debuts in late October, will either carry her closer to that pop Valhalla whose only current spirit is Madonna, or prove with a decisive stroke that the bubble of bubblegum pop has finally burst.

Spears prefers not to overponder her place in the pop pantheon. Its not that deep, she says, laughing, as she extends her fingernails to a manicurist who has suddenly appeared on the terrace. She is not quite the apple pie she seemed nearly five years ago, and yet theres no specific career gambitno obscure force other than the force of adolescent developmentworking to make Spears into a more complex and sophisticated act. Still, the turning point in her career seems all the more noteworthy at a moment when some critics are beginning to wonder whether Madonna has finally lost her edge.

Madonna, over? Spears shrieks, incredulous. (Heightened emotion tightens the twang in her Louisiana accent.) Then she reflects for a moment. Honestly, thats why I work so hardbecause thats a fear I have for me, she says. She pauses and swills her Red Bull. There are always gonna be people that dont love you, and actually, I kind of like the people like Madonna, who makes such a statement that people either love her or hate her. I dont want to be in between. I think thats boring.

Only the most jaded tabloid reader would be bored by accounts of Spearss life over the past few years. Her two-year relationship with Timberlake was the most famous musical coupling since Kurt and Courtney, and she has clearly been wounded by the breakup and the ensuing media storm. The most painful thing Ive ever experienced was that breakup, she says. We were together so long and I had this vision. You think youre going to spend the rest of your life together. Where I come from, the woman is the homemaker, and thats how I was brought upyou cook for your kids. But now I realize I need my single time. You have to do your own thing: be self-loving, you know. I know it sounds cliché and cheesy, but I really believe that if its meant to be, its meant to be.

For a young woman whose avowed virginity has been examined under the media microscope, Spears is surprisingly frank about Timberlake. Ive only slept with one person my whole life, she assertsshattering the dirty dreams of Humbert Humberts everywhere and veering at long last from the oft-repeated soapbox talk about no sex before marriage. It was two years into my relationship with Justin, and I thought he was the one. She pauses and her voice leaps an octave. But I was wrong! I didnt think he was gonna go on Barbara Walters and sell me out.

Spears, as every amateur pop-culture critic knows, has mastered a kind of in-your-face sexuality that seems to hedge in the same hot breath. She has worn a nude body stocking onstage and talked about her prayer diary in interviews; she has sung about how shes not that innocent while regularly inveighing against premarital sex. Its an oscillationthats what shes done so adeptly, says Barry Weiss, president of Jive Records. Britneys a good girl, but when the mike comes on in the studio, she becomes a vixen. Music literally transforms her. Its a wild thing to watch. Thats the erotic charade mounted by most child stars, who peak before they become consenting adults, and then find themselves frozen, as adults, in childhood.

The fun thing about my new album is there was a sneak peek of sexuality on Britney, but on this one I can kind of go there a little more, push the envelope a little bit, she adds, then raises her voice. But its not tacky! Its kind of sensually done. I think when things are too much in your face, then theres no subtlety in it. She pauses, backpedaling. Tacky can be fun, though, sometimes.

True enough, but the moment calls for something a bit more cosmopolitan. The photos accompanying this article suggest that it is J.Lo, after all, whom the grown-up Spears may be looking to emulate. I love J.Lo, she says. Im totally inspired by her. The whole put-together thing is usually where Im a little off, though. I dont like it so contrived. Normally I just do the tight jeans and the little shirt, whatever. But sometimes I want to wear a sequined dress and be a freakin girl! W is all about seeing yourself in a goddess sense, so I totally wanted to go there. Which isnt to say shes not still Britney. Honestly, though, she hastens to add, if everyone thinks Im gonna come out and be a woman, theyre wrong.

Along with a heightened glam factor, the new album finds Spears making a more ambitious use of heavyweight producers (or, more accurately, composers). Their role cant be underestimated, and in Spearss case, nearly every big name in the business lobbied for a piece of the pie. She stayed away from the ubiquitous Neptuneswho fashioned her house-inflected hit Im a Slave 4 Uinstead giving Redzone, an Atlanta collective, an opportunity with a few thumping dance songs that define the up-tempo feel of the album. Spears is especially pleased with the collaboration: her words, their rhythms. Theyre the first people Ive ever worked with where its like Im listening to it off the radio, she says. Where Im, like, yeah! Im jammingwith myself. And its weird. Ive never done that before. The record is also likely to include tracks by Metro, the English producers responsible for Chers nightmarishly successful single Believe, and the Matrix, engineers of Avril Lavignes biggest hits. P.Diddy and Moby have also weighed in. The song we did is kind of brooding and atmospheric, Moby writes in an e-mail. Its very simple and, for lack of a better word, sexy.

A far cry, certainly, from the rousing version of Sinéad OConnors Nothing Compares 2 U that a nine-year-old Spears once offered from the family trampoline in Kentwood, Louisiana (population 2,500). By that age, Spears had proven herself such a determined performer that her mother, Lynne Spears, decided to say goodbye to Kentwood and bring her daughter to New York to attend the Professional Performing Arts School. Within a year Britney had landed a part in an off-Broadway play and won a Star Search competition. Then at age 11 she moved to Orlando, Florida, to join future teen-pop stars Justin Timberlake and Christina Aguilera on TVs The Mickey Mouse Club. That was the best childhood experience you could possibly have in your whole life, she says. I mean, you live in Disney World! A few years later, the Backstreet Boys and the Spice Girls were saturating the airwaves, and Spears landed a contract.

I would have gone nuts in a classroom, she says. That wasnt for me. I started homeschooling after the eighth grade, and I didnt experience a real high-school thing. I think, when I went through a little party phase last year, it was because I didnt get a chance in high school to partyto go out and be stupid.

Which is a shame, since Spears loves to be goofy. She burps before offering a ladylike Excuse me, snorts when she laughs, loves to put on silly accents, and says things just because they sound funny to her. Why do I keep saying in the hizzy? she asks, giggling. I dont know what it means. Its like my ghetto form or something. (Fans of Snoop Dogg will know that its hip-hop slang for in the house.)

Shes 21, and thats what people forget, says her best friend, Jenny Morris, who may sing backup during Spearss next tour. We joke about it all the timeshe always says, If they only knew what a big dork I am. She loves to poke fun at herself. I think she honestly forgets how big her life really is.

The media also tend to gloss over Spearss youth when they catalog her barroom escapades: Stories about Britney getting sloshed and dancing on tables have made New York tabloid headlines ever since she began spending more time in the city just over a year ago. She swears the truth is less interesting. I wish my life were like that! she says. Honestly, I would much rather go to Crunch or lie in my tub and look at the bubbles. Really, Britney? Well, there was one night three weeks ago. I didnt dance on the tableit was the sofa. And everybody was standing up, the whole club was, and I stood up for a few seconds, and so now Im a wild girl and I stand on tables. Julia Roberts, she did that too! Listen to me, Im venting. Yes she didhell, yeah!

Its hard not to believe Spears when she insists the press has embellished her wild side, if only becausethese days, at leastshe makes so little effort to hide her less demure behavior. I was never hiding anything, she says, holding up her pink, rhinestone-paved Versace lighter to a cigarette and shrugging when asked why the tabloids made such a fuss recently over her smoking. It was the people around me that were hiding me. The publicists would call me and they were like, Oh, my God. This was in the newspaper. And Im like, Cool. I mean, what are you going to do? I think if I sat there and tried to hide it, it would look kind of stupid. Honestly, because I know Im not supposed to do it, it makes me want to do it.

And as for her sex life, Spears has some news that may cause a national outbreak of chest-beating. American boys (and Fred Durst especially) arent really her thing anymore; Spain and Australia, she says, boast the most alluring and least fuddy-duddy men. Oh, and Irelandvia Hollywood. The Colin Farrell rumors were true, she acknowledges: Yes, I kissed him. Of course I did! Hes the cutest, hottest thing in the worldwooh! Hes such a bad boy. But it was nothing serious. Since Farrell, her needs have gotten even more basic. Seriously, I havent had a boy in a really long time, and Im really cravingjust a kiss, man. Just a kiss would be nice.

Just a kiss? Now that the innocent act has supposedly gone the way of glitter makeup and Spears seems rather like the woman she threatened to be at age 17, a sweet little peck sounds almost regressive. Indeed, she has a big chance right now to emulate her professed idol, Madonna, by redefining herselfsharpening the talent, tightening the image and reflecting the emotions of her grown-up fans. It was Madonna, after all, who said Spears had been a victim of the same snobbery with which she was greeted in the eightiesand if Madonna has had the last laugh, so can she.

Spears clearly relishes another chance to defy her critics. If the records goodif its hot and you see the video and were working it, its basically saying the F-you to everyone out there, she says. And I think thats cool.