The important thing about the National Theatre of the Deaf, said David Hays, its director, is that it is not social work. "It's entertainment, it's funny stuff," he said. And if some social good happens to come out of it in the way of showing both hearing and nonhearing people another dimension of deaf people, so much the better.

On Wednesday, the Theatre will have its 3,000th performance, a milestone it will celebrate in the Terrace Theater at the Kennedy Center with its current production, "Parzival," which opens today. Last week its members were in Moorehead, Minn., and next week they'll travel to upstate New York. The troop's performing life is spent on the road, from Idaho to India, and it claims the distinction of being the only traveling company that has performed in all 50 states.

It also may be the only theater that was created thanks to the U.S. government, which still provides most of its funding through a grant that now comes through the Office of Education. In the 1950s it was HEW. "It's not a theater in their eyes," said Hays. "It's a device to bring jobs, help toward eradicating prejudices about deaf people, and to inform about different kinds of people."

A proposal in the mid-'60s from director Arthur Penn and actress Anne Bancroft, then fresh from "The Miracle Worker," never came to fruition, and in 1967 Hays revived the idea. Until this year the group was part of the Eugene O'Neill Memorial Center in Waterford, Conn., but recently split off to move to Chester, Conn., and a former factory built in 1801 to manufacture auger bits. "We were just tenants at the O'Neill Center," Hays said. "And we couldn't afford to stay."

The new move will cost about $250,000, but Hays is confident the funds can be raised somehow. "We can deal with it," he said determinedly.

Hays is not deaf, nor did he know anyone who was when he first saw a production at Gallaudet College over 20 years ago. It inspired him, a designer of numerous Broadway shows, to investigate the form, and ultimately to spend his life at it.

Plays are not translated literally from language into signs, but the two interspersed to produce a unique mix of pictures and words. Few things are beyond their grasp--they've even done two operas--Puccini's "Giannischicci," and Virgil Thompson's "Four Saints in Two Acts"--the first without music and the second with kazoo accompaniment. "I suppose I wouldn't choose a play where the characters spend most of the time on the telephone," Hays said. "But other than that I see no limits."

"Parzival," written by Hays and resident playwright Shanny Mow, is a variation on adventures from King Arthur's Court, "interspersed with the personal quests of the company members themselves." There are 12 actors, of whom three speak.

Most of the deaf performers in the "Children of a Lesser God" were alumni of The National Theatre of the Deaf, and some are still affiliated with it. "That show was an adroitly assembled commercial property," said Hays. "We're totally different."