After months of speculation and several weeks of very public auditions this spring, the National Symphony Orchestra announced yesterday that Nurit Bar-Josef would become its new concertmaster beginning next season.

Bar-Josef, 26, is currently the assistant concertmaster of the Boston Symphony Orchestra. She will become one of the youngest players in this country to be concertmaster of a major orchestra.

Bar-Josef replaces William Steck, who officially retired at the end of the current season but has not appeared with the orchestra since last fall. Insiders say his departure was not amicable.

The new concertmaster is NSO Music Director Leonard Slatkin's strongest single chance to put a personal stamp on the orchestra he has led since being named to the position in 1994. Since then, he has appointed 27 of the orchestra's 100 members, but no appointment is so fundamental to the sound of the group as concertmaster.

Bar-Josef has had a brief but distinguished career as an orchestral player. She is a graduate of the Curtis Institute of Music and has studied at Juilliard as well. She left Juilliard early to go into orchestra work. Before her position in Boston, she was the assistant principal second violin with the St. Louis Symphony in 1997-98; that was Leonard Slatkin's previous orchestra, but he was no longer with the group during Bar-Josef's tenure.

"Orchestras weren't a huge part of my life growing up," Bar-Josef, a Boston native, said in a recent telephone interview. "But there's this funny thing: My mother found a journal I wrote in third grade, when I was 8 years old, and in the bottom of one of the entries I had written that when I grow up I want to be in the Boston Symphony."

Bar-Josef says she is attracted "to the old-school-type playing."

"My absolute favorite violinist is Fritz Kreisler," she said. "The musicianship, the warmth, the technique. Next to him, other players have their strengths, but I don't honestly have a favorite among them."

Bar-Josef's father is an Israeli-born environmental engineer and geologist, and her mother is a secretary. She describes them as music lovers.

Enough so that they drove her from Boston to New York every weekend during Bar-Josef's high school years so she could study in the prestigious Juilliard pre-college division. She studied in the studio of the renowned pedagogue Dorothy DeLay; she also studied with Zinaida Gilels, the niece of the eminent Russian pianist Emil Gilels.

Bar-Josef's audition included interviews and three concerts with the orchestra in which she performed as concertmaster. She displayed a warm and expressive tone in brief solo lines in Mahler's Symphony No. 1.

"I didn't know what it was going to be like," she said. "I was nervous and anxious before arriving in D.C., but the process was very fair. I had a really great meeting with Leonard in the morning, and he put me totally at ease. He said, 'Treat the orchestra as if it's your own. Do what you need to do, say what you need to say.' The people in the orchestra were very friendly. It seemed like a big family."

Bar-Josef was one of four candidates for the job, including the NSO's current associate concertmaster, Elisabeth Adkins. Yesterday's announcement, which barely mentioned Steck, singled out Adkins's contributions to the orchestra during the past season.

"During the many weeks where she was asked to lead, she provided stability and the highest musical standard to the chair," said Slatkin. "Having Elisabeth and Nurit together on the first stand would be any music director's dream."

Nurit Bar-Josef, 26, beat out three other candidates for the job.