The gaffe was the funniest part of the evening -- and the party hadn't even started.

There was Arthur Mitchell, founder of the Dance Theatre of Harlem, standing on stage at the Kennedy Center, during an intermission in his ballet, ready to present an award to Cicely Tyson. Up in the Presidential Box -- the president and Mrs. Reagan, the vice president and Mrs. Bush.

"Mr. President, Mrs. Reagan," said Mitchell. "Mr. Vice President, Mr. Muskie --" There was a pause, and then Mitchell grimaced. "I'm sorry, I mean Mr. Bush."

The house went wild with laughter. Finally Cicely Tyson was introduced. "Mr. President, Mrs. Reagan," she began. "Vice President Bush, Mrs. Bush . . ." The audience roared, and Mitchall shook his head, hand to forehead.

Still, it was a memorable evening for other reasons. In addition to the chief executive, some of the highest-ranking Republicans in the administration came out for the occasion and some then went off to the party afterward at the Embassy of Sudan. Deputy chief of protocol Morgan Mason and East Wing staff director Peter McCoy chatted in one corner while Kennedy Center head Roger Stevens, National Endowment for the Arts head Livingston Biddle, and former National Endowment for the Arts chairman Nancy Hanks wandered about the room. And of course, there were Mitchell and Tyson.

Too bad the ambassador from Sudan couldn't make it.

"He's in the Sudan," said Minister Ahmed El Tinay, greeting guests at the door. "He had been planning this trip a long time."

"This is my first party here," said Peter McCoy.

"Ever?" asked Morgan Mason.

"Yes," McCoy said.

"You're handling it very well," said Mason.

McCoy accompanied Carolyn Deaver, wife of Michael Deaver, deputy chief of staff in the Reagan administration. "He's babysitting his kids," and my wife is babysitting my kids," said McCoy. "Next week we trade."

The Reagans didn't make it to the party, but it did not go unnoticed that their maiden voyage on the cultural scene was to the Dance Theatre of Harlem. "We though it would be a very good thing if the president knew the Dance Theatre of Harlem was in town," said one official from the Washington Performing Arts Society, which sponsored the company's performance. "He said he wanted to do a lot for the black people. To me the ballet was a natural."

Rep. Tom Evans (R-Del.) and his wife Mary Page had a little something to do with getting the Reagans to come. "I just saw Jim Brady [Reagan's press secretary] at a cocktail party, and said, 'Wouldn't it be nice if the Reagans came to the opening?'" Mary Page Evans said. "I think it's symbolic, they're supporting the arts."

"Isn't this fabulous?" said Rep. Evans. "The first president to view the Dance Theatre of Harlem is Ronald Reagan, and it's in his first thre weeks. All he had to do was have it suggested once."

Next to Arthur Mitchell and Cicely Tyson, Tom Evans was clearly one of the most popular men at the party.He was greeted with hugs from his friend Mitchell. He sat in the Presidential Box at the ballet. Verne Orr, secretary of the Air Force, greeted him with, "Thanks for all your help in getting me where I am. I've been meaning to drop by and say hi . . ." And Livingston Biddle pulled him over for a rather sober discussion. "Oh, he's just thanking me for my support of the arts," said Evans. A little while later, Biddle pulled him aside for some more chatting; the National Endowment for the Arts could face a 50 percent cut in funding according to the proposals in David Stockman's black book.

Cicely Tyson was there to receive an Emergence Award from the company for her support. "I don't want to say what my contributions were," said Tyson with a grin. "I did teach the dancers acting. After Martin Luther King was assassinated I remember that Arthur called me and said, 'Come over. I've got something to tell you. I want to start my own company.' He would go and pick up kids off the street. And that's how it started."