Eddie Vedder is 40.

Forty!

It wasn't so long ago that the Pearl Jam singer seemed ageless. With his band perched atop the charts in the early 1990s, Vedder was the popular symbol of a generation, a flannel-clad prophet giving voice to the disenfranchised acolytes of music called grunge.

Grunge's followers were tagged with the label "Generation X," and the media dissected the motivations and modi operandi of young people commonly regarded as sullen slackers. That turned out not to be the case, of course — Gen-Xers overcame the economic recession of their early post-college years to play a key role in the '90s tech boom and grew up to be reasonably well-adjusted citizens, parents and neighbors.

Yet misconceptions linger and are even codified in things such as "Whatever: The '90s Pop & Culture Box" (Rhino), a new seven-CD compilation of music that completely misses the point about the relationship between Gen X and the music of the 1990s. Now, as the leading edge of Generation X begins following Eddie Vedder into middle age, it's time to more carefully examine the musical legacy of what has become pop culture's middle child, wedged between the marketing cash cows of the baby boom and Generation Y.

GRUNGE, AND SOME

"In part, the story of the '90s is one of a demographic blip, of a particular age group having its brief, shining moment in the media spotlight," rock critic and author Jim DeRogatis, 41, writes in the liner notes to "Whatever."

That's true, but it's not the whole story. Generation X is indeed inextricably linked to the grunge explosion of the early '90s. But its glory years also included a powerful roots-music movement, the mainstream rise of rap, the downfall of the aberration known as hair metal and the beginnings of what will surely form the foundation of Gen Y's legacy: emo. From Minneapolis in the early '80s to the death of Kurt Cobain and the dissolution of Uncle Tupelo in 1994 — symbolic end points that are as strong as any — Gen X's musical legacy is staggeringly diverse.

Yet boomers continue to overshadow it, mostly because they can't shut up about the classic rock that is their cultural bequest. Gen X is also saddled with ambivalence about its own role: Many of the most-lauded bands between 1980 and 1994 never sought fame, and many of the ones that achieved it felt almost guilty.

"That is an underreported story: How great that period was for music and also what a conflict it was for the artists involved in it," says Tom Morello, 41, who played a key role in that period as guitarist for Rage Against the Machine.

The musical culture of Generation X is popularly believed to have been a revolt against the hair-metal debauchery of the late '80s. Actually, it began even earlier, as a younger age group reacted to the monolithic self-absorption of the baby-boom generation: 76 million people born between 1946 and 1964, according to demographers. Their development mirrored that of rock 'n' roll, and early boomers were children of post-war prosperity who witnessed the Beatles and Bob Dylan push against the boundaries of music. They basked in the mud at Woodstock and demonstrated against the war in Vietnam. They knew what it was to be young, man, and they haven't stopped talking about it since.

Their children noticed and, as children do, rejected the things their parents held dear. Those children, 41 million of them born between 1965 and 1976, were dubbed Generation X (though some definitions extend Gen X to 1978 or '79).

"Suffice it to say, that term self-served a generation of people who were disappointed by their inability to enthuse their children in a Jimi Hendrix-solo version of the American Dream," American Demographics magazine declared in May 2004.

Thus, punk rock.

Punk was the first musical reaction to the classic-rock ethos of the Woodstock generation. The original punk rockers were late-period boomers eager to distance themselves from the supercilious upper end of their demographic, and their music, reflecting the dour economics of the late '70s, became a template for Generation X and the ensuing "post-punk" movement that eventually birthed grunge.

SCENES NATIONWIDE

Assigning a birthplace or starting date to Gen X music is completely arbitrary, but let's say it began in the early '80s as part of underground scenes in towns such as Minneapolis and Athens, Ga. That's where the likes of Husker Du, the Replacements and R.E.M. co-opted elements of punk — the music in some cases, the attitude and independent mindset in others — and made music reflecting values that were their own.

"Regional scenes have been around for centuries" in art and literature, says Joan Hiller, 26, a publicist for Sub Pop Records, the independent Seattle label that released Nirvana's first record in 1989. "It's human nature to want to be around others of a similar mindset, and to want to look at the ideas around you regionally and take them and add something individual and grow that idea into something else."

There were other post-punk scenes in other cities throughout the '80s: Boston yielded Mission of Burma and the Pixies. Dinosaur Jr came from Amherst, Va. Fugazi hailed from Washington, D.C. Metallica moved from Los Angeles to the Bay Area, where it fused the speed of Misfits-style punk with the volume of Motorhead and Black Sabbath. St. Louis gave rise to Uncle Tupelo, which kick-started alternative-country with its blend of punk fury and working-class country honesty. And there was Seattle, which became a catch-all for the vibrant Pacific Northwest scene that included Pearl Jam, Soundgarden, Sleater-Kinney, Bikini Kill, Mudhoney and others. Nirvana, a Seattle band, pushed punk into the popular consciousness in 1991 when it released "Nevermind."

"It's as deep a well of talent and excitement as has ever come down the rock pike in a short period of time," says Morello, who underpinned the L.A. scene with Rage Against the Machine.

Punk was music obsessed with credibility, and nothing was more credible than rejecting an older generation's symbols of success. In the music business, that meant bands snubbed overtures from the major record companies, those stodgy gatekeepers, and released their music on independent record labels with such names as Dischord, Matador, SST and Sub Pop. Eventually, though, bands that patterned themselves after the original post-punk acts started to become popular outside their own scenes. In many cases, they were unable to reconcile the competing notions of indie cred and mainstream success.

"Most of them suffered in various ways from that arena-rock guilt," Morello says. "For some, it killed them, like Kurt Cobain. For others, it caused them to pull the plug on their massive success, like Pearl Jam. Other bands, like Nine Inch Nails, Tool and Rage Against the Machine, were so conflicted by it that they made a record only once every five years."

If punk started as the music of economic rebellion, it had a spiritual cousin in hip-hop. Rap was also obsessed with credibility, yet there was no similar ambivalence about popular success in rap music, which began as a street-level form of self-expression in New York City's poorest neighborhoods in the late '70s and has grown to dominate post-millennial pop culture.

Hip-hop is "arguably the single most significant achievement of our generation," Bakari Kitwana writes in "The Hip Hop Generation: Young Blacks and the Crisis in African American Culture" (Basic Civitas Books, 2003).

By "our generation," though, Kitwana means black people born between 1965 and 1984. "Generation X," he argues, is a term that applies primarily to whites, who are less conflicted about the split hip-hop represents in the black community. For all its cultural acclaim, Kitwana writes, rap music has foisted negative stereotypes on a generation of black youths, who are inundated with glorifications of "anti-intellectualism, ignorance, irresponsible parenthood and criminal lifestyles."

Subdividing Gen X isn't so easy, though, given the far-reaching influence Kitwana's hip-hop generation has had on its predominately white counterpart. A former punk-rock trio called the Beastie Boys showed that white kids could rap with "License to Ill" in 1986, and a straight, short line connects Grandmaster Flash, Public Enemy, Rage Against the Machine and Limp Bizkit.

FINANCIALLY ATTRACTIVE

By the time the likes of Limp Bizkit arrived in the mid-'90s, bands like Nirvana and Pearl Jam had demonstrated, however reluctantly, the financial possibilities of their music. The dollar signs attracted new bands that didn't share their predecessors' misgivings about commercial success, and rap and rock reconnected in the '90s, both as a short-term rap-metal musical fad and a longer-lasting business philosophy that placed a premium on material rewards.

"Bands that had much less artistic ability, much less credibility, but could ape the sounds of that first wave of important bands just came in and filled the void," Morello says. "Whether it was Limp Bizkit, which was rock-rap, or Bush, which was kind of Seattle-ish, they were all bands that were willing to do whatever it took."

The arrival of those bands, beautifully symbolized by the release in 1994 of Green Day's "Dookie," signaled the end of Gen X's period of musical primacy.