Loren Kitt. (Scott Suchman/Scott Suchman)

Loren Kitt, who served for more than 40 years as one of the National Symphony Orchestra's de facto leaders in his role as principal clarinetist and became a quiet cornerstone of Washington's classical music scene, died Sept. 4 in a hospital in Glens Falls, N.Y. He was 76.

The cause was bladder cancer, said Paul Cigan, the NSO's acting assistant principal clarinetist.

With his restrained elegance and sleek gray hair, Mr. Kitt was a familiar figure to Washington audiences, both for his NSO performances — including a number of solo outings — and as a founding member of the Smithsonian's resident chamber ensembles in the 1970s. He also taught and mentored students at the Peabody Conservatory in Baltimore and the University of Maryland.

One of his signature pieces was Aaron Copland's clarinet concerto, which he first performed at the first-ever Capitol Concert in 1979, under the direction of Copland himself. "Copland was pretty good, I think," he told The Washington Post last year, with typical understatement. "He eschewed the modern fast tempos and loud playing. He'd say to the brass, 'Noble, gentlemen, noble. I don't understand why everyone takes this so fast.' "

He played the concerto with Copland six different times. After the first performance, in 1979, Post classical music critic Paul Hume wrote that Mr. Kitt "played as if the music had been a part of himself for a lifetime."

Loren Wayne Kitt was born in Bremerton, Wash., on July 8, 1941. He began performing at 3 when he and his sister put on a song-and-dance number for troops stationed at Fort Lawton, near Seattle, during World War II. He didn't start clarinet until the fifth grade, inspired by his father's love of jazz musician and bandleader Benny Goodman.

In high school, a teacher took him to hear the Philadelphia Orchestra, on tour, playing Tchaikovsky's Symphony No. 4. The concert was a turning point in his life, he recalled.

"I skipped school the next day and practiced all day," he told WAMU-FM host Kojo Nnamdi last year. Soon he was playing well enough to perform regularly with the Seattle Symphony.

His serious interest in sports and dancing was curtailed when he broke his leg during a football game, after which he devoted himself to music full time.

After graduating in 1963 from the Curtis Institute, the elite music conservatory in Philadelphia, he was principal clarinetist with the Milwaukee Symphony and taught at Oberlin College in Ohio before Antal Dorati, then the music director of the NSO, hired him in 1970.

Mr. Kitt played his final official concerts with the NSO last February but came out of retirement to play a final time with the NSO for Mahler's Second Symphony in June, one of Christoph Eschenbach's last concerts.

His first marriage to violist Cynthia Field ended in divorce. Survivors include his wife of 34 years, Catherine Collins Kitt of Camden, Maine; a daughter from his first marriage, Sandra Kitt of Falls Church, Va.; a daughter from his second marriage, Karen Kitt of Camden; two stepchildren, Cynthia Sherwood of Glens Falls and Christopher Clusen of Fort Collins, Colo.; a brother; a sister; and three grandchildren.

Mr. Kitt and his wife had moved to Camden full time in 2003 from Alexandria, Va., and he commuted between Maine and Washington for the remainder of his NSO tenure. "He was one of the great musical leaders of the orchestra," Cigan said. "We've lost an incredible musical voice."