CYNTHIA ROWLEY: SASSY AND STYLIN'.

Byline: Barbara De Witt Daily News Fashion Editor

Cynthia Rowley may be from New York, but she's a Valley Girl at heart.

In town for the Emmys last weekend, the 38-year-old designer went for the sassy look with a killer white halter dress that showed off her taut body and a bouncy ponytail.

She likes to have fun with fashion - and is, like, totally amused by people who take fashion too seriously. So don't freak out when you step into her L.A. boutique that has a frog on the door that says ``Kiss me'' and giant tiaras decorating the shelves. She's a Leo, by the way.

``Fashion is entertainment, and I think fashion shows should be a show, not just a bunch of girls walking the runway,'' said Rowley, who received the 1995 Council of Fashion Designers of America award for best new talent and whose playful designs are catching more publicity as various celebrities put them on.

She's been called the ``queen of theme'' with her quirky takes on traditional fashion shows, inviting firefighters, musically inclined family members or celeb friends - including Molly Ringwald and Claire Danes - to perform on the catwalk alongside professional models wrapped in knitted mufflers over breasts to mimic halter tops.

Although she's done some outrageous shows and ensembles - including a swimsuit with wings - this year Rowley is steeped in '70s nostalgia and uses the P-word often (``polyester,'' that is). She loves Quiana, that slinky, thin poly-fabric that's a fave with rummage sale shoppers.

``It was the fabric of my day, and I always made my prom gowns out of it ... and I'm still wearing it,'' Rowley said of the short cocoa-brown Quiana shift dress she wore for her interview.

With entertainment-oriented shows and a simulcast of her fashion show on the Jumbotron in New York's Times Square, Rowley was soon the fashion darling of television talk shows, including ``Late Show With David Letterman'' and ``MTV House of Style.'' Approaching celeb status herself, Rowley has become a favorite of young Hollywood with a growing list of fans that includes Helen Hunt, Lea Thompson, Nancy Travis, Karen Duffy, Mira Sorvino, Gwyneth Paltrow and Natalie Merchant.

Rowley says she only dresses stars who are nice.

``To some people, it seems like I'm a newcomer, an instant success, but I was working 12 years before anybody even cared,'' said Rowley, who is helping other young designers reach their goals through the Bacardi Limon BreakThrough Fashion Design Search. The contest offers nonprofessional designers a chance to showcase their funky, cutting-edge talents and compete for cash prizes and an internship in New York City with Rowley. Finalists' designs will be modeled by celebrities and supermodels at the final competition (date to be announced), which will be an AIDS fund-raiser sponsored by DISHES (Determined Involved Supermodels Helping to End Suffering).

For more information on the contest, call [phone], or write to Bacardi Limon BreakThrough Fashion Design Search, 1500 Broadway, 25th Floor, New York, N.Y. 10036. Deadline for receiving entries is Sept. 30.

Rowley, who lives with her husband, Bill Keenan, in Manhattan and on a small farm in upstate New York where she has a small menagerie of livestock, said she began her career with a small grant, some money from her grandmother and an eight-piece collection.

Reflecting on her new-found success, she said, ``People don't realize that it's way more work than glamour, and the hardest part of being a designer is the pace. You have to have a million new ideas every day, but I love the creative outlet, from the sketches to the technical production,'' she said. ``And I guess the best advice I could give is to be realistic about your dreams and work really, really hard.''

This year's hard work has resulted in a '70s tribute that includes Quiana turtleneck dresses with macrame belts, split-leather pants with turtleneck sweaters, Shetland sweaters with plaid bias-cut skirts, cable-knit cardigans and matching caps and mufflers, tiny satin satchels (she calls them lipstick totes) and big Lucite (plastic) cocktail rings. Her favorite silhouette is pants, which she calls the ``ultimate in chic,'' especially with a fitted turtleneck sweater.

The color of the season? Rowley says she's heavily into the Browns Age, with dozens of customers in line for her oxblood brown-leather pants, but stay tuned. She predicts that by spring '98, designers will be back to black.

Meanwhile, you can find Rowley's fashions at her boutique at 112 S. Robertson Blvd., Los Angeles, as well as Saks Fifth Avenue, Nordstrom, Bloomingdale's and Macy's. She also has boutiques in New York and Chicago and plans to open 12 additional boutiques throughout Japan.

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4 Photos

Photo: (1-3--Color) Fashion designer Cynthia Rowley, top , loves brown, finds pants the ultimate in chic and gets inspiration fromt thrift-store finds. Among her fall designs are a ``Love Story''-themed sweater with cap and muffler, above, and a red Qiana day dress, left.

(4) Metallics look fresh again in Cynthia Rowley's gold and silver knit separates, accented with an arm cuff and Mary Janes, available at her L.A. boutique, Nordstrom and Macy's.