Image from the New Haven premiere of "Love Fail." (James Matthew Daniel)

Ten years ago, the composer David Lang was a maverick outsider who was tolerated but somewhat patronized by the classical music establishment: too light, too pop-influenced, too superficial. Today, David Lang has won the Pulitzer Prize and a Grammy, been featured at Carnegie Hall, and has just been named Musical America’s Composer of the Year.

“I’m really sort of amused by it,” says Lang, 55, of his newfound prestige. “After [you win] the Pulitzer, people go, ‘It’s okay to listen to your music now.’”

Lang’s latest work, “Love Fail,” is an example of the kind of circles the onetime outsider is moving in these days. Its roster of co-commissioners include the Brooklyn Academy of Music and the Kennedy Center’s Fortas Chamber Music series, which will present it at the Terrace Theater on Wednesday night; and it was written for the popular a capella vocal group Anonymous 4. Not bad for a composer who used to be better known for organizing 12-hour marathons of music by himself and other composers nobody had ever heard of.

The thing is, Lang isn’t doing anything different. He’s still helping put on marathons along with his two co-conspirators, composers Michael Gordon and Julia Wolfe, with whom he founded the collaborative Bang on a Can in 1987; they’ve since founded a performing ensemble, a record label (Cantaloupe Music) and a summer music institute, and this year’s marathon drew upwards of 10,000 people. He still believes that classical music needs to be more open to influences from other kinds of music — pop, jazz, world music. He still writes thoughtful, quirky pieces, though arguably with less of the in-your-face quasi-bratty humor of earlier works such as “Cheating Lying Stealing.”

It’s just that finally, a lot of his ideas are being more widely embraced by the music world, and the classical establishment is at last able to look past its erstwhile horror of the “crossover” label to appreciate the music Lang writes.

David Lang (Peter Serling)

The obvious watershed was “The Little Match Girl Passion,” the piece that won the Pulitzer Prize in 2008. It’s hardly a flashy piece: a half-hour long a cappella work for a vocal quartet. It was conceived as a way a Jewish composer could join the heightened world of suffering and transcendence depicted in Bach’s great passions: a religious oratorio based not on the life of Christ, but on Hans Christian Andersen’s story “The Little Match Girl.” Lang thought he might encounter backlash on religious grounds; instead, the work’s mixture of spareness and profundity had a powerful effect on many listeners.

Although Lang didn’t think of the work as a major stylistic departure, there were a couple of things that set it apart. For one thing, Lang largely abandoned the slightly satiric stance he had often adopted in the past — though there is some humor implicit in the idea of turning the story of “The Little Match Girl” into a religious work, the result was actually pointed and direct. “I think because I was trying to be honest with myself,” Lang says, “people realized something personal in it for them as well.”

Another innovation is that Lang wrote, or adapted, the text himself. “It’s relaxing as a composer,” he says. “You’ve done your structural thinking before you go in and write the music.” He says, “I knew what the music was supposed to do already by the time I wrote it.”

Lang has done several pieces involving research and writing in the years since, and “Love Fail,” at an hour long, is the most ambitious yet. It focuses on the legend of “Tristan and Isolde,” filtered through its various retellings so that what emerges is not the love story per se — Tristan’s and Isolde’s names are never mentioned — but a 12-movement narrative of love that intertwines the salient details that distinguish one version from another. The narrative is bound together with short stories by the writer Lydia Davis, whose wry, contemporary take on love fit a work that Lang, writing for the early-music specialists Anonymous 4, wanted to lift out of time altogether. “I wanted to do something about the clash of spending so much time with music 800 years old and being a modern person,” he says.

“Love Fail” is also conceived as a theater work, albeit without an explicit story, sets, or costumes. “You know how now we’re always thinking concerts have to be more than concerts, [with] video and lighting,” Lang says. “I thought, if that’s going to be a viable strategy for a concert, then all those extra elements have to be treated as carefully as any play or opera. If you’re going to add an element, it has to be completely measured and shaped and cared for.” The work is thus enhanced with carefully calibrated lighting effects by Jennifer Tipton, a sound design by Jody Elff that gives different enhancement to the different movements, and equal attention to every other detail. Even the chairs the performers sit on are specially designed; “I want to take them home,” Lang says. The point is to create a and every detail thought out down to the chairs the performers sit on, of which Lang says, “I want to take them home.” The piece works fine without the theatrical components, but what the performers do in the theatrical version “is completely supercharged by what the designers have done.”

“Love Fail” turned out to be the largest commission Anonymous 4 has ever done, though it wasn’t conceived that way; according to Jacqueline Horner-Kwiatek, one of its members, the group initially approached Lang about writing a single short piece for its 25th anniversary. The singers aren’t complaining. Lang, says Horner-Kwiatek, “sat in rehearsals with us, watched how we interact, and [got] to know our individual voices — we have very different voices.” She adds, “When he wrote for us, he played to our individual strengths as well as the group’s strengths” — including a solo for Horner-Kwiatek near the end, which she says she’s thrilled about.

“One of the things I love about the way David writes,” she says, is that “he writes in silences. He writes in bars of rests after the piece ends. . . . I love how in a capella music silence is part of the piece, part of communication. There’s something about the stillness and simplicity and yet complexity of what he’s done.” And, she adds, “Also, it’s funny. . . . That’s the nature of love; sometimes all you can do is laugh.”

Lang bears this out in his musings on the nature of romance, and the way that looking at myths of Tristan and Isolde helps us either forget or process the nature of our own loves.

“Every single love story on Earth is a tragic love story,” he says, and invokes the artist Suzanne Boccanegra, his wife and mother of their three children. When the two were on their way to City Hall to get married, he says, “she looked at me, jabbing the air with her finger: “This is an agreement that one of us will bury the other. She meant it romantically.”

Anonymous 4 sings “Love Fail”: Wednesday at 7:30 p.m. Kennedy Center’s Terrace Theater. 202-467-4600.