Reprinted from yesterday's late editions The Crowd started froming before Sunday night. By the time Nat Adderley's quintet came on, more than 5,000 persons had gathered in the grassy valley that is the Fort Dunpont Park Summer Theater in Northeast Washington.

People stretched out on blankets.Mothers pushed infants in carriages and carried them in their arms. Youngsters parked their bicycles near where they sat. One man pitched a tent and had 10 friends join him.

Under a big yellow moon, people drank wine from cups or straight from the bottle. The pungent smell of marijuana swept the area. Photographers bunched together in front of the stage, searching for the right spot for the right picture.

It was a Jazz festival setting - like the Newport Jass Festival used to be, before it moved to the concert halls of Manhattan. While Adderley's group moaned the blues, many people strolled casually around the grassy knoll, talking with friends or enjoying the cool summer evening.

"It's a nice way to spend an evening," said Bill Minor, who described himself as a music lover. "This is beautiful for Nat Adderley. All these young people getting to hear live jazz."

The Adderley group and Tim Eyerman and East Coast Offering were the lastest performers in the current season for the Fort Dupont Park Summer Theater Program. It opened June 25 and 26 with Hank Crawford and closes Aug. 22 with Lionel Hampton. The Alvin Ailey Repertiore Dance Ensembel appeared July 1 and 2 Upcoming concerts will feature Betty Carter, Sun Ra and Rahsaan Roland Kirk. The concerts, sponsored by the National Park Service and National Capital Parks-East, are free.

Al Dale, director of the Fort Dupont Summer Theater program, said the series had gone well so far - "much better than I thought it would. We've used dance groups and some drama groups. We're trying to make it a complete theater."

In its fourth of operation. Dale said the program had worked primarily on word-of-mouth publicity and a modicun of advertising from WHURFM, the Howard University radio station.

"People come here from all over the metropolitan area," he said. "When the Alvin Ailey dancers performed, the audience was about one-fourth white. When the Dinizulu African Dance Troupe played, we had a lot of black nationalist types. We could tell by the way they dressed. Now we don't know what kind of crowd to expect when (avant-garde jazzman) Sun Ra plays."

Adderley, who's led his own group since the death of his older brother, Cannonball, two years ago, charmed the crowd with the fervent blues singing and crisp cornet playin. Saxophonist John Stubblefield also lit up the audience with his fiery, circuitous melodies.

After the last note was sounded, the crowd disappeared quickly in cars and on foot - remarkably so, without the help of any law enforcement officers.