After all the ball gowns and glamour, the jiggling beads and flashy sequins, and in spite of every hour spent at the hairdresser, it took one 81-year-old actress in black pants, a long black coat and a pair of black sneakers to make everyone else look as though they had gone to a lot of bother.

Katharine Hepburn, her hair pinned up in a wispy topknot, walked into the Kennedy Center last night to applause from hundreds of guests lining the entrance to the Opera House. It's fair to say that a lot of them were waiting just to see her -- to see if she would, in fact, wear black pants. And there she was, kind of marching along with her escorts, her black suede bag slung over one shoulder as if she were taking a hike.

"She has her own style," said Georgette Mosbacher, who certainly has hers. Mosbacher wore a pleated black haute couture gown from Christian Dior and a massive rhinestone cuff on each wrist. They looked potentially dangerous. "They're very useful," she admitted, flexing her muscle. "They keep your upper arms in shape."

On the whole, the attire for the evening was fashion punch: a lot of black spiced up with Santa red (most notable Angela Lansbury in a less-is-more gown) and iced with cold, cold sequins. Carmen de Lavallade had on a gold brocade ballgown designed by her husband, actor Geoffrey Holder, who said he selected gold "because it would brighten things up." Dina Merrill wore black lace and Lynn Redgrave went black, but with a flourish of white satin around the knees. Sisters Debbie Allen and Phylicia Rashad effectively nixed the hemline question: Rashad wore a sari and Allen a coquettish pouf. Evangeline Bruce also went north of the knees, in a black Yves Saint Laurent dress with a peeking red petticoat. As for Michele Lee, it wasn't so much the color of her gown that people noticed but its plunging decollete. She said the dress was by Anne Klein, but did that matter?

Watching guests arrive earlier at the White House -- between a row of potted trees and a portrait of Grover Cleveland -- was a lesson in star power. The big fish drew the photographers' flashes, while the small fry drew hardly a passing glance from the press line. But some of them posed anyway. James Woods, the actor, stopped long enough for his date, Julie Tesh, in a plain black strapless gown, to be photographed. John Candy -- the original Uncle Buck -- stood next to the potted foliage with his wife, Rose. And Glenn Close stopped to elaborate.

"I couldn't honor Hepburn without wearing pants," she said. "This is Ralph Lauren, Armani, Cerruti and this is an antique scarf." All "this" added up to an understated black pants ensemble with a nifty belt.

Such understatement, however, was not the norm for an occasion that usually brings out the Scaasi in people. That's Arnold Scaasi, as in the white camellias around Sara Aronson's shoulders. "Kitty Carlisle told me she has the same dress," said Aronson, whose husband, Leonard, was Massachusetts Gov. Michael Dukakis's treasurer for 10 years. Carol Winer of Potomac waltzed through the Kennedy Center crowd in a gold brocade pouf -- the kind of fashion that made the '80s so much fun. "Actually, I cut it off," she said. "It was a long dress when I bought it."

Slung over her shoulder was a gold evening bag with the telltale linked C's of Chanel. But unlike Hepburn, she didn't look ready to take a hike.