Gold and red banners fluttered from the roof of the Thai Temple near Montgomery Hills yesterday, an occasional breeze wafting through the yard where 500 people celebrated Kaopansa, one of three days marked most reverently by Buddhists each year.

It is a day on which Thais and other Buddhists pledge themselves to renewed spiritual vigor, in the ancient Buddhist tradition.

While celebrants feasted on shellfish and noodles, youths in embroidered costumes performed ceremonial dances depicting stories from Buddhist mythology.

Yesterday marked the beginning of a three-month period of meditation for the three temple monks. The period, which coincides with the rainy season in Thailand, is begun on a day marking the anniversary of the first sermon by Buddha to his first five disciples 2,529 years ago, said Dr. Krita Apibunyopas, vice president of the Wat Thai Association, which administers the temple.

The temple is in a split-level house on Georgia Avenue but is being moved shortly to the monks' residence on Layhill Road in Silver Spring. To begin the move, the 400-pound statue of Buddha was taken by truck to the new site in the late afternoon.

Darting between the booths where Thai food and wares were being sold, Washington resident Sivilai Samung served as hostess to newcomers unfamiliar with Thai culture.

"It means so much to have people from outside our community to come to the temple where they can experience our way of life," said Samung, 42, a secretary at the American Association of Retired Persons. She moved to this country from Bangkok 12 years ago.

Apibunyopas said the 12-year-old temple is a source of security for Thai people. "Because we have staff that can speak the language and understand their customs, the Thai community comes here for most of their social, economic and religious needs," he said.

Dr. Anong Lekagul, director of the Thai Culture and Performing Arts Association, has accompanied young dancers from the temple when they have performed at the Kennedy Center and at area schools. She says audiences become "entranced in the music and movement" of the performances.

"Young people who were born to Thai parents in America and never had a chance to visit" Thailand are attracted to the dances and customs, said Lekagul, a gynecologist and obstetrician from Kensington.

Sean Gallagher, 15, one of two novices ordained during the day's celebration, sat quietly in the temple, wrapped in an orange robe.He will be taught prayers and the monks' customs during the next week.

Dressed in red and purple embroided satin, 12-year-old Yomphana Adams rested behind the stage where she had performed a lotus folk dance in honor of Buddha.

"These festivals are important to my people," said Adams, a U.S. native whose mother was born in Thailand. "You learn about all the American stuff" but "now it's time to concentrate on our own culture. Sometimes you just get sick of hamburgers and you want to eat Thai food," she said.