Most of the time, she's Beth Harmon, 24, a shy, brown-eyed young woman who wears jeans and T-shirts but no makeup.

But then there are the times she becomes Sa'Diyya (pronounced "Sa-DEE-yuh").

She puts on her makeup and sequins, her silks and lace -- she has 20 ornate, glittering Turkish or Egyptian-made costumes that help her transform herself into a woman of power, confidence and sensuality.

"Sa'Diyya is me and then some," Harmon says.

As Sa'Diyya, she performs as a belly dancer in area Middle-Eastern restaurants, such as Hedary's and Byblos, and for special events. Restaurant patrons are typically delighted by her performances, but they might not realize they're seeing the best of the best. On Memorial Day weekend, Sa'Diyya won first prize at the Belly Dancer of the Year Pageant in Walnut Creek, Calif.

Harmon is part of a thriving belly-dancing and Middle-Eastern ethnic dance community that involves dozens of professional and part-time performers in the area, as well as hundreds of enthusiastic amateurs.

"I was 14 when I first saw a belly dancer at a Greek restaurant in Dallas," Harmon says. She doesn't remember the name of the dancer she saw. But she remembers the performance, which changed her life.

"There was glamour," she says. "There was a beautiful costume. For me, it was a powerful, feminine image."

Harmon had been interested in performing all of her life; belly dancing's reputation as a form of female-repressive seduction didn't occur to the 14-year-old as she watched that dancer move to the gentle, almost fragrant Middle Eastern music. Instead, the teen-ager saw a form of art and self-expression in which one woman was in charge.

So Harmon sought out belly-dance lessons and discovered the Isis Star Dance Studio in Bedford, just a few minutes away from her parents' house in Colleyville.

Harmon's parents hoped that belly dancing was just a phase for Harmon. After all, few Texas parents dream that their daughters will grow up to be belly dancers.

"They paid for the lessons," Harmon says. "They figured I would get sick of it."

But instead she became more and more fascinated. Setting aside her natural shyness, she stepped forward for her first public performance as a belly dancer in the 12th grade, in a talent contest at Grapevine High School. She took third prize -- and started an intoxicating buzz among her fellow students.

For a stage name, Harmon first called herself "Shi" after an ancient Egyptian goddess. She changed to Sa'Diyya, which means good fortune, after she realized that her friends thought that Shi (pronounced "shy") described her personality.

After graduating from Grapevine High School, Harmon studied tap dance, jazz and art at Texas Wesleyan University; she decided after two years to focus on belly dancing, but she intends to return to school next January to study business and art. She's still relatively new to the art: She gave her first paid professional performance on New Year's Eve at Byblos restaurant.

Currently, Harmon lives at home with her parents and earns money teaching and dancing. She dances mostly at restaurants, where a good belly dancer can pull in up to $200 an evening in tips and base pay. Because costumes can cost $200-$1,000, it's definitely a low-profit-margin activity.

But she saved enough money to enter the Belly Dancer of the Year Pageant.

The competitive pageant was founded 30 years ago by the Bay Area dancer and teacher known simply as Sula. It is now run by Leea Aziz, one of Sula's pupils.

While one could hardly call it a national or international championship, Aziz says that it is the oldest, continuously operating competitive belly dancing pageant in the world. Though belly dancing involves thousands of people around the world, the competition circuit is still comfortably small and modest.

"Other pageants model themselves on us," Aziz says. "People who want to compete here will do other pageants first for practice."

Through the years, the Walnut Creek pageant has grown from one event, Belly Dancer of the Year, open to all ages and both genders (though no male dancer has ever won), to four separate events. Twenty women and one man entered the Belly Dancer of the Year division, the highest level, in 2003. It offered a $500 first prize. About 800 people attended the event at a performing arts center in Walnut Creek.

Harmon, who decided to enter at the last minute, took with her what she considers her two most flattering costumes -- and music that was upbeat and varied in tempo.

But winning wasn't her main goal.

"I went to have fun -- and to see other dancers," she says.

The modern Egyptian dance style she uses made her stand out in a field dominated by the Turkish-Greek style more common on the West Coast. Of course, belly dancing is ultimately not about competing; Harmon says the atmosphere at the pageant was relaxed and friendly.

And she says she has returned from the pageant with a heightened enthusiasm for the art form.

In spite of its reputation in the West as a form of seduction, belly dancing originated in the ancient Middle East as a social dance performed by women for women, partly as a means of strengthening the abdomen in preparation for childbirth -- a sort of early Lamaze. Americans first heard of belly dancing when a troupe of dancers from Egypt appeared at the Chicago Exposition in 1893; the Western term "belly dancing" may well be a corruption of its original name "beledi," which 19th-century viewers of the bare-midriffed dancers may have heard as "belly dancing."

By the 1970s, there was a large, active belly-dancing community in the United States.

But there were, and still are, many divergent directions and concepts. The type currently most popular in America, heavily influenced by Egyptian custom, makes much use of props -- such as the zills (finger cymbals) and the shamadan, or candelabra. Veils are also important and have religious significance in some forms of belly dancing, representing the separation and reunion of humanity and God. Whatever style a dancer uses, says Harmon, it is an art form of beauty and self-awareness.

"It's not about seduction," she says. "It's totally feminist. It's about girl power."