Next to the president of the United States, you can always depend on a movie star to jazz up a Washington party. The dazzle of the marquee plays rather well in the solemn world of politics--even if the lights haven't been lit in a while.

Douglas Fairbanks Jr. was here last night as honorary chairman of the CARE Birthday Ball, and it was as though the 300 people gathered at the Organization of American States building had never been to the movies before. The clicking of pocket cameras managed to drown out the rustling taffeta. And scores lined up to meet the actor who says he now dabbles in the New York business world.

"I do one play a year, and that's about it," said Fairbanks, who hit his stride as an actor in the '40s. "Like any good gambler I quit while I was ahead. It was a strain to stay on top, especially with the five-year gap because of the war. So I decided to go in other directions. I'd much rather have people ask me why I stopped acting instead of 'Why don't you stop acting?' "

The ball was in honor of the 36th birthday of CARE--an organization started after World War II to supply food, clothes, cigarettes and other staples of life to needy European countries. The little packages are still arriving, but many of yesteryear's receivers are now donors for developing nations.

Fairbanks was one of the original founders of CARE, and has been traveling and fund-raising for the organization ever since. Last night's event was expected to raise about $75,000.

"It's always a good way to remind people that don't particularly like Americans that we're human beings," said Fairbanks.

The evening began at dinner parties sponsored by 13 embassies around town, including Australia, Chile, Greece, Haiti, Italy, Japan and the OAS. Everyone respectfully raved about the food. "The Italian was fantastic," oozed one woman. "It was some kind of veal." And over at the Jordanian Embassy, the okra was flown in from Jordan. Guests were impressed. The OAS served Chicken Olympus in champagne sauce and an elaborate dessert comprising pastry, chocolate and vanilla cream topped by strawberries.

"It's called Breast of Paris," said a waiter, who said he used to be an accountant, but just opened his own janitorial business and moonlights to support that business. He also works part time in a travel agency. So he carries two business cards. "I got tired of investment banking," he said, over the pineapple-and-melon platters in the ballroom.

The attire was black tie and everyone obliged, except one elderly man who came in dress kilt. And danced in dress kilt. "I know Americans tend to get ridiculous at times, but this takes the cake," mumbled one South American jokingly under his breath. Pastels were the uniform for the ladies. They showed up nicely against summer jewels and the beginning of chestnut tans.

The hosts for the evening--OAS secretary general Alejandro Orfila and his wife, Helga--welcomed guests with their usual flourish and panache. Helga boogied enthusiastically, white slit skirt flowing, long legs flashing. And the Argentine-born ambassador dodged questions on the Falkland Islands crisis.

"Everyone is asking me questions--even the bandleader, he asked me," said Orfila. "I made a commitment not to talk about it. NO COMMENT."

Yellow and blue balloons flapped, and the band played "Don't Cry for Me, Argentina."