Michael Tilson Thomas, the American conductor, composer and pianist whose 25-year tenure as music director of the San Francisco Symphony became a model of collegial music-making, artistic adventurousness and community engagement, died Wednesday at his home in San Francisco. He was 81.

The cause was glioblastoma, an aggressive form of brain cancer, Constance Shuman, his publicist, said in a statement.

Thomas announced in the summer of 2021 that he had had surgery for a brain tumor. In March 2022, he specified that he had been diagnosed with glioblastoma.

Although Thomas’ prognosis seemed ominous and he was forced to cancel some scheduled performances, for more than three years he rallied and led a number of inspiring concerts.

In February 2025, he announced that his tumor had returned, and he conducted his final performance that April, in a return to San Francisco for a belated celebration of his 80th birthday.

Thomas was a technically crisp and sensitive pianist, especially during his early years as an adept exponent of contemporary scores, and a composer with a small but striking and stylistically diverse catalog of chamber pieces and songs for voice and orchestra.

He was also the best teacher and demystifier of classical music for the general public since Leonard Bernstein — a popular pedagogy that Thomas carried out through award-winning television programs, videos and online educational sites.

Still, from the day his high school orchestra director unexpectedly tapped an oboe-playing Thomas to take over a rehearsal, he seemed destined for the podium. As his career developed and he increasingly committed himself to conducting, he found himself suited to a role that demanded both musical and leadership skills. He was also openly gay at a time when nearly no one else of his prominence in classical music was, and over the years in San Francisco he became a local gay idol.

Thomas explained the role of a conductor in an American Masters profile that aired in 2020. Its title, “Michael Tilson Thomas: Where Now Is,” was taken from his statement that a conductor’s job involved “getting 100 people or so to agree where now really is.” (The phrase was inspired by a line from the James Brown song “Cold Sweat.”)

He expounded on conducting in an interview with the Times in 2002. “I am like a director who has the luxury of being able to see the big scene,” he said, “and be very helpful at focusing the ensemble and encouraging a section or an individual soloist to deliver a line expressively.”

Before he took the helm of the San Francisco Symphony, Thomas had conducted most of the world’s major ensembles; held the post of music director of the Buffalo Philharmonic in New York for eight years in the 1970s; served as principal guest conductor of the Los Angeles Philharmonic from 1981 to 1985; and was principal conductor of the musician-run London Symphony Orchestra from 1988 until 1995, when he began his San Francisco tenure.

Thomas said his approach to formidable symphonic scores was akin to visiting a national park. “I know the map well,” he told the Times in 2014, “yet being on the trail is always a new experience, and who you are with changes it entirely.”

Still, ambitious projects and experimentation defined his time in San Francisco. He fostered contemporary music by forming relationships with living composers. He inaugurated American Mavericks festivals that brought attention — and drew large youthful audiences — to pioneering, flinty composers like Charles Ives, Ruth Crawford Seeger, Henry Brant and guitarist John McLaughlin. He reimagined the concertgoing experience by incorporating video technology to present semi-staged productions of works.

That he was ideally suited to music education was already clear during the 1970s, when for six years he was music director of the New York Philharmonic’s Young People’s Concerts, the televised venture that helped make Bernstein a household name. Thomas took this work further in San Francisco, creating a series of “Keeping Score” videos in which he explored the backgrounds of seminal works.

Michael Tilson Thomas was born Dec. 21, 1944, in Los Angeles, the only child of Ted and Roberta (Meritzer) Thomas. His father, born Theodore Hertzl Thomashefsky, was a stage manager and producer for New York theaters and later in Hollywood. Thomas’ mother established the research department of Columbia Pictures and later taught at public schools in the Los Angeles area.

When he was 12, he met a fellow student, Joshua Robison, then 11, while both were members of their middle school orchestra.

Years later, they reconnected and, in 1976, became a couple. They married in 2014. Robison, who was Thomas’ manager and producer in numerous creative projects, died in February. Thomas leaves no immediate survivors.

Thomas enrolled in the University of Southern California in 1962 to study piano with John Crown and composition and conducting with German American composer Ingolf Dahl.

A big break came in 1968 when Thomas, as a fellowship student at Tanglewood in Massachusetts, worked with Bernstein, who became a lifelong mentor and colleague, and won the prestigious Koussevitzky Prize for student conductors. The following year he was appointed assistant conductor of the Boston Symphony Orchestra.

His official debut with the orchestra in the fall of 1969 proved auspicious. “Resisting the temptation to prophesy,” Boston Globe critic Michael Steinberg wrote in his review, “let me say simply that right now he is one of the ablest and most interesting conductors in the profession.”

Later that year, when William Steinberg, the Boston Symphony’s music director, became ill during a program at Carnegie Hall, Thomas, then 24, had to take over for the second half.

The event was a triumph.

As Steinberg recuperated, Thomas wound up leading the orchestra in 37 more concerts. In 1970, he was appointed associate conductor of the Boston Symphony and made his London debut with the London Symphony Orchestra that same year.

Steinberg was slated to step aside in 1972, the year after Thomas became music director of the Buffalo Philharmonic. But there was talk in Boston musical circles of whether Thomas might have a future in Boston as well. Michael Steinberg explored the question in a January 1972 article for The Boston Globe Magazine.

Yet, as the Globe article reported, some players in the Boston Symphony were reacting negatively to what they perceived in Thomas as aggressive precociousness, bratty outbursts and a penchant for having them repeat passages in rehearsals without saying why.

Looking back, in a revealing 1976 interview with the Times, Thomas said that in Boston, he “was not joyous about the spirit of music-making that was going on” and that “he got tired of looking at people whose eyes were totally dead,” whose “defensive grimace” kept conveying that “‘this is not the nobility of Beethoven!’”

Thomas focused his energies on Buffalo and other ensembles. His reputation as a restless renegade with an arrogant streak lingered. Then, in 1978, at 33, he was arrested at Kennedy International Airport and charged with carrying a small amount of cocaine, some marijuana cigarettes and a few amphetamine tablets. He pleaded guilty to disorderly conduct in a plea bargain.

The incident tarnished his public image, as he later acknowledged in a 1995 article in The New York Times Magazine.

“People found out I was not the model of a nice Jewish boy,” he said. “The event pushed me from wunderkind to desperado. It hurt, and I probably did not get some jobs I might have gotten, but hurt is important and instructive for a musician.”

He forged on, appearing with major orchestras, growing increasingly in demand and making recordings, more than 120 over his career, earning 12 Grammy Awards overall.

Ever since his association with Tanglewood, Thomas worried for the futures of talented musicians in the insecure world of classical music. In 1987, he realized a dream. With the support of Ted Arison, the owner of a cruise ship line who had once hoped to become a concert pianist, he founded the New World Symphony, a professional training academy based in Miami.

The academy could be a “launching pad for people’s lives,” he said.

“My personal mission,” he said, “is to have them hold onto ‘What does this mean?’ I’m trying to give the larger message of what music is all about.”

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This article originally appeared in The New York Times.

By Anthony Tommasini/Lauren Lancaster
c. 2026 The New York Times Company