The young woman who turned heads at last night's party was wearing a flapper dress from the '20s and a headache band.

There were parasols and turn-of-the-century white dresses at the embassy garden party.

Edwardian gowns aren't uncommon.

It's antique chic, and if your own grandma didn't hand down her dresses, you can buy what you want at several Washington stores. "I don't think the trend has peaked yet," says Harriet Love, whose Soho boutique in New York is credited by some with starting the craze.

You can wear these dresses just as they were meant to be--a '20s evening dress at the Kennedy Center, or a '30s wedding dress at your own. Or you can buy them and turn them into something else--a ruffled Victorian petticoat becomes a skirt, or a dress if you add a camisole for a top.

Either way you'll avoid the department-store look-alikes, and probably undercut prices, too. At least one outlet rents vintage clothes for the weekend.

Victorian dresses, with their romantic embroidery and ribbons, are splendid for getting married in. Jameson & Hawkins, one of the top antique fashion stores, has them at $150. Try to find anything with handwork at anywhere near that price today and you'll see why business in vintage chic is up. Evening dresses from the '30s through the '50s go for between $100 and $150 here, and you won't see one just like it on anyone else.

If you're not getting married, try a Victorian blouse, beautiful with lace and tucks, with your own '80s skirt. The department stores have plenty of reproductions, but few are handmade like Grandma's. Mary Martin bought an authentic one at Jameson & Hawkins, whose name, by the way, is taken from the maiden names of the mothers of the two owners.

The Great Gatsby in Alexandria has blouses as well as dresses from 1890 on (and some of them turned up at last year's inaugural gala).

There is at least one problem with the Victorian dresses: Our grandmothers had 18-inch waists.

"They were corseted, remember, from the age of 2," says Joan Bradley Cohen, owner of the Great Gatsby. Both she and Carol Franks of Jameson & Hawkins can advise you on how to cope with the squeeze (by raising the waistline, inserting a dart or a bit of elastic). You may have to let out some seams in the arms. (They also had small arms back then.)

Turn-of-the-century fashions look appealing on young girls but older women are finding them fun, too. Women in their forties are buying the nightgowns, belting them with an interesting belt and pairing them with sandals for sailing parties and resort wear. Cohen wears one of her Victorian slips for a beachcoat. Trousseau knickers, like the ones Scarlett O'Hara displayed when she picked up her skirts to run, make nice pedal pushers.

There's no getting around the fact that the materials in these clothes are delicate and must be treated with the respect accorded the aged. Asked how she cleans her stock, Franks replied, "Carefully." Cohen washes the laces in liquid Lux.

Beaded dresses from the '20s are special problems and should be kept rolled in tissue paper. One Bethesda woman who sometimes wears her mother's '20s beaded and jet-trimmed gown to parties says she sheds like a Christmas tree if she's not careful. Top-of-the-line vintage clothing stores sell only those in top condition, so these dresses are fairly rare in many stores.

The gowns of the '30s are hardest to wear. Think of Jean Harlow, poured into her satin gowns and dragging on her long cigarette holder, and you'll know what kind of a figure you must have.

The little numbers from the '20s with no waistlines fit nearly everybody, but the real bargains probably are the designer suits from the '50s, especially Adrian and Ben Reig, and Irene from the '40s. At Jameson & Hawkins, you can buy these for about what they once sold for, as testified to by the ads in the period Vogues the store keeps on the coffee table.

Men get into the act, too. At Geraldine's, on upper Wisconsin Avenue, you can rent antique suits for the weekend, plus derby and opera cape, top hat, the works. They even have two-toned shoes with pointed toes.

Bring the children. Many of these places have linen sailor suits and sashed dresses like the ones children wore in Vogue photographs 50 years ago.

And then there are the hats. Big "Hello Dolly" hats, the velvet cloches of the '20s, and for the men, wide-brimmed fedoras like those Humphrey Bogart wore.

At Geraldine's, you can rent the wide-lapeled ice-cream gabardine suits of the '20s gangsters to go with the fedoras. Most devotees of vintage chic avoid the look of pure costume, but Geraldine--"I'm into costume"--can make you into anything from a WWII aviator to Miss Piggy.