STYLE; The Standard-Bearers

'We were acquaintances, and we were at this party 2/3'' the actress Zooey Deschanel says, explaining the genesis of ''If All the Stars Were Pretty Babies,'' the cabaret act she does with the actress Samantha Shelton. ''And they had this great jazz band, and I was, like 2/3 'Oh, I wish I could go up and sing,' and Sam said, 'Let's do it together.' So we went up and sang 'Summertime' in C, and people really responded, and we were kind of blown away.''

Sitting poolside at the Roosevelt Hotel in Hollywood, the scene -- fresh young starlets meeting the press while a team of beauty technicians lacquer their hair, nails, makeup and outfits -- is pure MGM.

And, indeed, the hotel, a classic Southern California amalgam of Mediterranean, Moroccan and English styles, in a city where the past is under constant siege from the future, fills a pair of shoes that newer, trendier hotels could never hope to fill. It was the site of the first Academy Award ceremony in 1929. Clark Gable and Carole Lombard regularly booked a penthouse suite for their rendezvous. A 50's suntan-lotion ad shows a peppy, smiling, unknown Marilyn Monroe perched on the diving board.

A breeze dapples the surface of the pool. Sun glints off the grass. Palm trees, their crowns 40 feet in the air, rattle the wind -- if ever there was a literary cliché about Los Angeles, this is it. Along with a team of technicians wrestling a temporary stage, a sound system and lighting into place for tonight's Pretty Babies party, David Rodgers, the party promoter, dives into the pool to arrange giant black and white balloons anchored with bricks into aesthetic coherence.

The gals troop dutifully back and forth between photo setups. Part Cafe Carlyle, part Little Rascals, the Pretty Babies -- backed by an eight-piece ensemble, including a piano (no keyboards for this act) -- are a breath of old-fashioned, big-city swank in a megalopolis not known for an overabundance of it.

And they are adamant about making clear that the Babies are not a pose. ''We're not doing an 'Oh, we're swingers!' thing,'' says Shelton, 24, who confesses that the Babies let her realize a longtime ambition to do a Weimar-era cabaret act. ''This is not tongue in cheek. We're not making a comment about these songs. We really love them.''

And while both of them are working actresses (Deschanel's latest movie, ''Manic,'' opened recently, and Shelton's new pilot, ''One Tree Hill,'' has just been picked up by the WB while ''Moving Alan,'' a film directed by her father, Christopher Shelton, makes the festival rounds), finding outlets that satisfy the need to sing sometimes demands that a girl take the bull by the horns. Except the bulls aren't always in the ring at the same time. So the Pretty Babies come out to shine only when work schedules allow.

''I'll be working on a job, and Zooey will be researching music,'' Shelton says. ''And then when she's working and I'm free, I'm researching.'' And then at some point, the universe conspires and gives them time to rehearse.

They both cite the usual suspects -- Judy Garland, Ella Fitzgerald, Billie Holiday, Rosemary Clooney, Dinah Washington -- when asked to list their inspirations, but from there, the eclectometer starts swinging. ''Cass Elliot was amazing 2/3'' offers Deschanel, 23, who does a solo version of ''Dream a Little Dream of Me.'' ''And Les Paul and Mary Ford harmonies are so awesome 2/3'' Shelton adds. ''Just when we think we're going to focus on jazz, we find some great country song.''

And so while you expect to hear ''Sentimental Journey'' or ''I Can't Give You Anything but Love,'' you can also expect to be taken to another place entirely by the Babies' versions of ''Just Because'' and the country-western weeper ''Honky Tonk Angels.'' They also delight in unearthing long-forgotten musical gems, songs that are so old, and so long forgotten, that the only place to find them is in sheet-music archives. ''My sister, Marley, found me a sheet-music song called 'Red Lips Kiss My Blues Away,''' Shelton says. The Babies had to learn the ukulele for that one.

And while it's not about a pose, the Babies aren't an evening you can pull off in a mini and a halter top. And so Shelton and Deschanel, who both confess to spending most of their time in jeans and T-shirts, go for celluloid-era glamour. ''Our first couple of shows, we bought slips, things we could find that were alike,'' Deschanel says. ''After we got tired of those, we started wearing old-fashioned stuff. I have a lot of vintage dresses and some stuff that looks vintage.''

And as the act has gathered steam, the ubiquitous stylist has entered the picture. ''We did a show at the Henry Fonda Theater,'' Shelton says. ''And Jessica Paster got us these amazing flapper dresses for one act, and we had these coordinating polka-dot dresses made for another, and gowns for another. It was so cool.'' Despite the glamour onstage, the production is downright folksy. ''Sam went to high school with our pianist and arranger, Graham Jackson,'' Deschanel says. ''And he brought a bunch of his friends in, and I had a friend from high school who plays guitar, and I brought him in.'' Adds Shelton, ''My sister will sometimes produce the show, and my roommates take the tickets.''

But will success turn the Pretty Babies into the Spoiled Brats? They seem rather unimpressed with themselves, thanks perhaps to their familiarity with life when the camera is rolling and when it's not. Shelton's father is a director, her sister is also an actress and her mother, Carol, sings and teaches school. Deschanel's sister, Emily, acts, and so does her mother, Mary Jo Deschanel.

''They're Hollywood successes, without the Hollywood attitude,'' observes Bryan Rabin, whose party-planning outfit, Rabin Rodgers, booked the Babies for an Oscar week party for WWD, as well as conceiving the setting for this evening.

Asked the classic question -- Where do you go from here? -- the two hesitate. ''Well, I don't know,'' Shelton says. ''Know anyone at a record label?''

''How would we tour?'' Deschanel worries. They consider. And seem to decide that for this moment the Pretty Babies' star is bright enough. Besides, there's a show in June to get ready for.