"I'm out of my teens," shouted Mark Bove last night to an impromptu chorus of "Happy Birthday."

But even so, he and most of the other dancers at the Kennedy Center were still younger than the production they were appearing in -- "West Side Story." It had opened 22 years ago here in Washington at the old Shubert Theater.

Roger Stevens, who was 20 years old and then some, was in the audience then and smiling. Last night he was still smiling as the curtain went up on the revival of the Broadway hit that was an adaption of Shakespeare's "Romeo and Juliet." In 1957, when the curtain went down on the show's world premiere here, Stevens had a happy hunch that he might have a hit on his hands.

"At the big investors' audition, not one person even wanted to put a dime into it," Stevens recalled. "I told Lenny [as in Bernstein] that I would underwrite it. It was a very profitable venture." He smiled broadly.

Last night a sellout crowd attended a preview performance that benefited The Green Door, a private, nonprofit, self-help program for individuals suffering from long-term mental illnesses. Afterwards they assembled in the Kennedy Center's Atrium for a supper honoring Bernstein, who wrote the music for the show, and Steven Sondheim, who wrote the lyrics. Neither, however, attended.

Jerome Robbins, who directed and choreographed it, turned up, as did Oliver Smith, who designed the scenery in both this and the original production. They shared a table with the benefit's general chairperson, Pamela Harriman, and her husband, W. Averell Harriman.

Robbins said he hadn't had too much time for nostalgia -- "I'm too busy working" -- so he left the comparisons of the 1980 revival and its 22-year-old ancestor to others among the several hundred supper guests.

Most of the performers said they first saw the show when it was a movie, and a couple told of appearing in it in summer stock. Brian Kaman, 22, who plays Baby John, who is 14, said he was 12 years old when he first played the role in summer stock.

When Mark Bove, who plays "Action," realized it was after midnight and he was 20 years old, G. Russell Weilandich, 22, who plays "Gee-tar," announced to the crowd gathering round: "The show is older than him."

At the theater, the Harrimans were joined by Rosalynn Carter and her daughter Amy as well as Mayor Marion Barry. Mrs. Carter, honorary chairperson of the event, came at the end of a day that saw her campaigning for the president in Iowa.

Mrs. Carter did not go on to the supper, but the White House was well represented anyway.

"We're all romantics at heart, that's why we're here," said presidential assistant Jack Watson.

Nan Powell, accompanying her husband Jody and their daughter, said she thought it was because "everybody just had to get out."

Stu Eizenstat, the president's assistant for domestic affairs, told of another buffet supper going on at the White House, this one being given by the president for 75 or so members of Congress.

"We invited a broad spectrum, including people like Sen. (Robert) Dole for a briefing on Iran and Afghanistan."

Like Jody Powell, Eizenstat said there was "no question" that the grain embargo against the Soviet Union had caught the Russians by surprise.

"I met with an exporter on Sunday who told me about a Russian he deals with saying they were absolutely flabbergasted."

Before the show, the Harrimans entertained at cocktails for 100 or so benefit-goers, some of whom paid as much as $1,250 a seat. Committee members expected to clear an estimated $100,000 for The Green Door.

At the Harrimans', guests included Oliver Smith, TV personality Kitty Carlisle; presidential assistant Anne Wexler; National Endowment for the Humanities chairman Joseph Duffy and Channel 9 anchorman Gordon Peterson. h

Green Door board chairman Joel Klein said the addition of Pamela Harriman and Gordon Peterson as supporters had helped the program's name-recognition. Starting out barely three years ago with about nine "members" (the word "patient" is avoided), there are currently 150 "members" being assisted in job training, social and recreational skill-building and other comprehensive self-help situations.

Klein said the board intends to negotiate to purchase the Worlich mansion, which it currently rents. Proceeds from last night's event will go toward that goal.

Klein said The Green Door grew out of the frustrations he and others felt three years ago when they found there was no place for former St. Elizabeth's Hospital patients to go to be absorbed into the community. He was a lawyer in a suit against St. Elizabeth's when a judge ruled that half of the patients had to be introduced into the community but there was no place to put them.

"We were tired of all the lawsuit stuff," said Klein, "so we decided to get a staff and start The Green Door."