Every corner has been turned into a land of fantasy at Wolf Trap this week-end, as the International Children's Festival takes over all nine stages of the country's only national park for the performing arts. The spectacle, a most delicious way to introduce children to all the arts and send them back to school with a smile, continues through 5 o'clock today. If you don't have a child, borrow one. There is no more pleasant way to spend this once-a-year picnic day.

At the opening on Saturday, music drifted in and out everywhere as children were made up as clowns near the Filene Center stage. At the foot of the steep hills to the south there was a showmobile set up, with the sounds of Offenbach's "orpheus in the Underworld" magically echoing with the breeze as the St. Matthew's Carol Bell and Joyful Ringers signaled the beginning of the fun. There were exotic dancers from India emerging from the woods in colorful saris, and folk singers in the Concert Shell spun Dylan melodies with all the sincerity of another decade.

The Murray Spalding Dance Theater made its Wolf Trap debut at the festival this weekend, with a little gem called "The Doubtful Guest." Choreographed in 1979, it is an almost too liberal dance translation of Edward Gorey's cartoon tale of an intruder in a Victorian home. Spalding herself danced the role of the mother, her body at times arched like an eyebrow and her lines clear and clearly romantic. This is modern dance with a longing look at the past, and with theater as its aim. The short Chopin preludes chosen underscored the episodic nature of the story, while the clear dance diction gave the illusion of an ominous night, even in the shady daylight of the Theatre in the Woods. David Cohen was the hysterical guest, his bloated costume including a tire concealed around his waist, his sneakers allowing him some very bizarre attitudes. Giggles of "What is that, mommy?" were buzzing at his entrance.

The father was danced handsomely by Steve Peters, and as the daughter Mary Guidicci was perhaps too subtle for the outdoor setting. "The Doubtful Guest," which will be repeated today at noon, has all the understated pomp and nostalgia of a Ronald Firbank novel, danced by a company that deserves to be seen in the likes of the Terrace Theater soon. Don't miss it at Wolf Trap today.

And as you run to see Spalding, the fantasy festival will go on. A disco magician called Myklar the Ordinary will do tricks, youthful Broadway belters like Dan Madigan and Brian Goldstein will put on a variety show, there will be folk dancing in every corner, and an exhibit of UNICEF paintings will be worth a second look. With a record number of smiles per minute, the Fairfax County Council on the Arts deserves the broadest of them all for sponsoring this Labor Day weekend hit.