In the summer of 1998, George Lewis was at work on his history of the Association for the Advancement of Creative Musicians, a black collective that formed on the south side of Chicago in 1965. He was transcribing recordings of the AACM’s early organizational meetings, and even though he was on a fellowship at Civitella Ranieri, a 15th-century castle in Umbria, and a warm breeze blew in through his window across a field of sunflowers, the meetings were so charged and engrossing that he almost forgot where he was. “I’m listening to some of the same people I’ve known all my life talking about things,” Lewis says. “The neurons started firing as I listened to this meeting, and I had the urge to say, ‘Hey! No, don’t do that!’ Or I was getting mad at the same people I would get mad at in a real meeting.”

Transcribing those tapes was just part of the decade of research and writing that would eventually go into Lewis’s landmark book, A Power Stronger Than Itself: The AACM and American Experimental Music, due early next month from the University of Chicago Press. It goes deeper into the formation and development of the AACM than any previous history, and as a formal acknowledgement of the group’s enormous importance and influence it’s long overdue.

In the early 60s the marketplace was indifferent or hostile to creative jazz, and the AACM was the first sustained musician-run group to support it, producing legendary artists like Anthony Braxton, the Art Ensemble of Chicago, and Henry Threadgill. The organization remains active today, led by reedist Douglas Ewart and flutist Nicole Mitchell, and its members still display the fierce determination and brilliant creativity that made its name a seal of quality.

Lewis himself joined the AACM in 1971, when he was in his late teens, and went on to become one of the world’s greatest trombonists and experimental composers. Though his own story is necessarily woven into the fabric of the book, he does a remarkable job balancing the voices of his nearly 70 interview subjects—not only does he avoid imprinting the material with his own biases, he frequently stops short of deciding which version of a contested event is correct. Members of Braxton’s regular trio and members of the Art Ensemble, for instance, are both allowed to take credit for the idea of briefly relocating key AACM artists to Paris in the late 60s and early 70s.

“I got a lot of e-mails from people saying what this person said can’t be in the book because it wasn’t true,” Lewis says. “I would say, ‘Well, they said the same thing about you!’ I had to avoid getting into a thing where the book does harm to the collegiality of the group, so I tried to take the approach of presenting as many different stories as I could.”

Born and raised in Woodlawn, Lewis entered the University of Chicago lab school in the third grade. Neither of his parents played music, but they thought their son would make friends if he learned an instrument. Lewis chose the trombone, he says, “mainly because it looked big, shiny, and weird.”

A new teacher named Dean Hey helped establish a jazz band around the time Lewis reached the ninth grade, and he quickly got involved. Before long he was studying privately with Hey and listening to his father’s neglected jazz records. His classmate Ray Anderson, another future trombone great, took him to hear saxophonist Fred Anderson, who would later become his mentor in the AACM. A year later Lewis encountered the Art Ensemble: “I was stunned by Joseph Jarman’s body-painted arms,” he writes, “attacking a vibraphone with mallets swishing dangerously close to my nose. I remember being so frightened that I literally seemed to faint.”

Lewis spent two years at Yale, studying music and prelaw, before deciding to take time off. Back in Chicago in the summer of ’71, he heard music coming from a building and followed the sounds. The band he found included pianist Muhal Richard Abrams and guitarist Pete Cosey, both AACM members, and they invited him to a rehearsal. It ended up being canceled, so they asked Lewis to come to their next gig instead, at a spot called the Pumpkin Room. He’d only been invited to watch, but he didn’t know that—still in his teens and accompanied by his protective parents, he showed up with his horn, expecting to sit in. They let him onstage and gave him a trial by fire. He doesn’t remember it going well, but under Abrams the AACM was serious about encouraging young musicians. A week later Lewis was playing a gig with Roscoe Mitchell, Steve McCall, and Malachi Favors, and within a year he was a member of the collective.

Most members of the AACM have had interests outside jazz—contemporary classical, sounds from Africa and Asia, electronic music—and Lewis is no exception. He’s played as a sideman with Braxton and collaborated with John Zorn and Derek Bailey, and even at the beginning of his career he was making radical departures from jazz orthodoxy. By the mid-70s he was integrating early synthesizers into his performances, and in the late 80s he rolled out the first of several fascinating interactive computer programs, a “virtual improvising orchestra” called Voyager, which analyzes and responds to human musicians in real time and simultaneously generates sounds based on its own internal processes. (A duet with the program on Lewis’s 2000 Tzadik release Endless Shout demonstrates its impressive depth and musicality.) In the late 80s he was a resident at STEIM, a prestigious Dutch center for “electro-instrumental” music. In 2002 he won a MacArthur fellowship, and he’s taught at a series of colleges—he’s currently a professor of music at Columbia University in New York.

In the mid-60s, of course, the kind of professional opportunities Lewis has taken advantage of didn’t necessarily exist for musicians like him. Avant-garde jazz hardly draws big crowds today, but 40 years ago it was greeted with incomprehension and hostility. The music business in Chicago was built on bars, and that meant club owners wanted jazz bands to play standards that people could drink to. The AACM wanted a concert atmosphere, so they found alternate venues and presented their own series. They agreed on a mission, established rules, collected dues, even ran their own school. The idea was to build a self-sufficient parallel system, however modest, where they’d be free to follow their own paths.

Naturally it took a great deal of wrangling to reach that point, and the tapes Lewis transcribed—which Abrams had held on to through the years—capture the vigorous, high-spirited debates of the AACM’s first months. One passage in his book relates a crucial argument about the definition of “original music,” which was what the AACM intended to support. Not everyone at the early meetings was comfortable with the most rigorous definition of the phrase. Some musicians, like bassist Melvin Jackson—most famous for the late-60s cult record Funky Skull—didn’t want to feel like they had to choose between being in the AACM and occasionally having fun with somebody else’s tune. “The only thing that I’m concerned with personally is good music,” Jackson said. “Just to say ‘original music,’ that’s not my mood all the time, it might not be your mood all the time.”

As the discussion evolved, “original music” came to apply strictly to material that was pretty experimental, but the AACM’s definition of the term was never rigid—though it excluded much of the already known, anything not yet imagined was fair game. The group was reluctant to carve anything in stone when it came to what its members should and shouldn’t be doing, and that openness surely contributed to the staggering diversity of the music they produced over the years.

Lewis knew from his own experience with the AACM that one of the group’s early concerns was to change not just their own terminology but the way other people talked about their music. But even he was surprised at how insistent they were about it. In the 60s, jazz was still a dirty word for much of the public. Historically thought of as black music, jazz was often dismissed as vulgar and lowbrow—certainly nothing to take seriously as art. It would be many years before the grant-making organizations that could’ve helped sustain a group like the AACM came around. “I listened to hours and hours of tape and nobody talked about free jazz or anything like that,” Lewis says. “I think people were looking for ways of revising the discourse and sensing either intuitively or explicitly that revising the discourse was key to revising their actual situation.”

More tense and contentious was the debate over whether nonblack musicians would be allowed to join the AACM—in fact, the issue was never formally resolved, merely set aside. It seems to have been settled off the record: Only one white musician, vibist Emanuel Cranshaw, ever belonged to the collective. He joined in 1967 and was voted out without his knowledge in ’69. But as rocky and imperfect a process as the formation of the AACM sometimes was, it still represented an unprecedented opportunity. “People were super stoked, it seemed to me,” says Lewis. “They were so excited about the idea that they were taking charge of their own destinies.”

Lewis didn’t expect A Power Greater Than Itself to take him more than ten years to finish, but it doesn’t bother him much that it did. “I’m glad it took that long,” he says. “When I started, certain people hadn’t attained the degree of musical maturity that they achieved later on, like Nicole Mitchell.” In the past few years Mitchell (who I profiled in the Reader last summer) has emerged as one of the most exciting flutists and composers working today. “When I finally got around to interviewing her, it was a good moment to do that,” he says, “much better than if it had been in ’97 or ’98.”

If Lewis has any regrets, it’s that he didn’t get the book done in time for some of the AACM’s most revered figures to read it—Lester Bowie, Malachi Favors, Leroy Jenkins, and many others died while he was working. “It’s always nice to receive a certain amount of vindication during your lifetime,” he says, “and certainly I felt that the people who started the AACM needed that.”

On Tuesday afternoon Lewis will appear at the Cultural Center with Ewart and Mitchell to discuss the history of the AACM and strategies independent artists can use to form similar collectives. Following the talk they’ll give a short performance.v