For Karl Lagerfeld, starting a new collection is like playing a new instrument. Tuesday he showed his first American collection, and it was a virtuoso performance.

It had all the makings of a Paris show -- the best models in the world, the crush of photographers at the runway, the fashion groupies. Even Catherine Deneuve showed up, slipping into her seat just before the show began. And most of all, it had Lagerfeld's limitless ideas.

He showed the best and the brightest sweaters seen so far, several interesting jacket shapes (including a nifty short turquoise blouson over a long skinny black skirt), wonderful white wool blouses (again with skinny black skirts), and some of the leanest black dresses around. And only Lagerfeld would put a big white duffle coat over a slinky dress.

The designer, who creates the Fendi Furs, the Chanel collections and his own line, calls this new effort KL Sportswear, but while it is less imposing and easier than his Paris collection, one could hardly call it casual. "That's a word I hate," said Lagerfeld.

Although he calls it his American line, mostly made in America with American fabrics, he sees little difference between women here and abroad. "Well-dressed women are the same everywhere," says Lagerfeld, who has never spent more than three or four days in New York at a stretch. "But then I never spend more than three or four days anywhere."

As in his Paris collections, there is a lot of black, a lot of tight skirts both long and short, and a lot of stretchy wool jersey. Some of the wrap and tie styles look complicated enough to need a set of instructions, and some evening dresses, made with elastic, were skinnier than ever. "People who buy expensive clothes," Lagerfeld said, "have expensive bodies."

Oscar de la Renta, who showed his collection this morning at the Parsons School of Design Auditorium, is also counting on women staying slim this fall. He uses shirring and draping for a narrow look, a favorite technique of many Paris designers as well. It works well in two-piece wool jersey or cashmere dresses for day or evening.

The collection is very ladylike, leading off with a series of handsome double-faced wool easy coats, worn over unmatched suits with blouses often adding a third pattern. He likes the short jacket, as in a black-and-white houndstooth check jacket worn over a slim black wool jersey dress.

De la Renta, who has always had customers for his glitzy clothes, proved he can take a simpler route for an elegant look. He did it with a series of shorts and blouses in hammered satin paired with full skirts in another pastel. A long, slim, two-piece white cloque' dress, shaped a bit with shirring on one side, was a real winner.

For those who don't feel dressed up without glitter, there were enough sequined blouses and beaded tops on skinny dresses to keep their closets full for years. And for those who can't make up their minds, the designer showed beaded sweaters with gray cashmere trousers.

Adrienne Vittadini, who masterminds some of the niftiest knits around, is also on the same wavelength as the European designers.

She has done a handsome American version of the rug and tapestry themes used by Byblos in Milan, Joseph in London and Jean-Paul Gaultier in Paris. Her versions are far more colorful and varied, and work well in all shapes and sizes of tops, including chemises, best with skinny pants, leggings or stirrup pants.

In a more subdued group, the Vittadini knits are like English tweeds, teamed with riding jodphurs and girls in horn-rimmed glasses. And she has picked up on the popular "Amadeus" inspiration, not only showing amusing hats, lace scarves and jewelry, but patterning knits to look like jacquards.

For evening Vittadini dressed up her knits with white-on-white sweaters in a paisley and jewel motif, paired with white moire' skirts and trousers.

The buyers loved it. "The spirit of the clothes is terrific, the colors are wonderful. It's perfect for the Washington woman," said Neal Fox, president of Raleighs.