Lisa Powell stood before the mirror backstage at Wolf Trap's Filene Center, brushing her long, brown hair, inspecting her silver eye shadow and rouged cheecks, smoothing the black material of her dance slacks around her hips. Only moments before, she was one of several children who had belted out "Tomorrow" from the Broadway musical "Annie" before a crowd of several thousand.

Powell, 13, was one of hundreds of youngsters with stars in their eyes who danced, sang, and, in some cases, literally backflipped their way onto several stages at the International Children's Festival at Wolf Trap during the long, hot, muggy Labor Day weekend.

For Powell and others like her, the festival was a place to be seen, a chance to perform before large crowds in a prestigious place, an opportunity to case the styles of other budding entertainers.

"Very few people get to perform in a place like this in their lives," said Susan Kraft, producer of the event, staged as a fund-raiser for the Fairfax County Council of the Arts, "and here they've got a captive audience." Held in cooperation with the Wolf Trap Foundation and the National Park Service, the festival drew more than 20,000 people to the park.

Over the woods the strains of Tchaikovsky mixed with those of Bob Devlin's harmonica. There was constant movement as children, followed by weary parents, ran from theater area to theater area, sure they would miss something important.

"For many people it's the only time they get to see a live performance. Theater is getting so expensive now. Where else can you get all this for $2.50?" Kraft asked.

With seven staging areas and continuous performances from 11 a.m. to 5 p.m. by a variety of international groups and local professionals and amateurs, kids were everywhere -- sliding down the wooden bannisters of the Filene Center, casting for minnows in the small streams that run through the park and huddled around the edges of the theater-in-the-woods stage where a python slithered down the arm of its trainer.

Barry Polisar, a 24-year-old self-described "children's satirist," drew a large crowd of picnickers on the hillside overlooking one stage into a singalong of "Don't Put Your Finger Up Your Nose." After his performance, Polisar, who performs during the year at schools in Virginia and Maryland was swamped by kids clutching $5 bills who wanted to buy one of his five records. In minutes, 25 albums were duly autographed and were safely tucked under the arms of children seen fanning out into the audience.

A man dressed in lederhosen and feathered hat strolled by, passed by a clown on a unicycle who dabbed red paint on the noses of all he saw. Babies in strollers began to rub their eyes while their parents sought out the shade of the trees that line many of the concert areas. Most wore a contented, well fed look.

A tall, blond teen-ager, after sitting some moments before a stage where a 12-year-old magician moved through his tricks, finally urged her family to leave. "This is boring," she said.