In rock 'n' roll, growing up is what you don't sing about. Pete Townshend's infamous battle cry of "I hope I die before I get old" captures the mythic vision of rock as the one true bastion of rebellious, unfettered youth. In our perfect rock 'n' roll dramas, the hero speaks (in rhyme, no less) the words we can't manage to unleash. With the mysterious power of an alchemist, he packs venom and longing and fear and sex into a handful of chords on the guitar. In the span of a three-minute song, he blazes through the gutsy, revelatory, unhinged life we long for. Or, in Liz Phair's case, our hero recommends sexual positions that maximize a good view of the TV.

But that was five years ago. Phair released Exile in Guyville, her debut album, in 1993, and instantly became the indie-goddess of good girls who just say yes. She was a 26-year-old upper-middle-class white chick who wrote foul-mouthed, lo-fi pop tunes in the bedroom of her parents' house in suburban Chicago. Guys, of course, dug Phair's good looks and loose mouth. But women found in her something altogether different. Phair gave astoundingly frank, deadpan voice to the silent majority of single females for whom life had somehow wound up a depressing string of one-night stands. She claimed to be a freewheeling fellatio queen one minute, and a self-loathing young woman stuck in a perpetual morning after -- pining for a real boyfriend, one who "made love because he was in it" -- the next. Her dilemma was modern, mythic, and totally rock 'n' roll.

Rarely had song and lyric found such naturally rough-hewn harmony. Phair's language of anti-love was blunt and dry as her singing voice, which scraped blithely across the bottom of her register. The words were raw and plain like her guitar playing, slippery as the remarkable melodies that twisted and turned as if they were trying to find a way out, or a way in, or both. Phair wanted it, for sure. But she wanted something more.

Growing up usually means growing out of it -- trading some of the hedonism and narcissism for a share of grown-up gratification like comfort and stability, marriage and family. Following 1995's commercially and artistically disappointing Whipsmart, Phair checked out of the music business and began taking care of other business: She married her video-director boyfriend and gave birth to a son, who is now 1 1/2 years old. Her new CD, whitechocolatespaceegg (Matador), is very much a product of those life changes. Thoughtful and mature, deeper and more expansive both lyrically and musically, these songs fall head over heels into polished pop without squashing Phair's quirky melodicism and slipshod delivery. And for skeptics who doubt that domestic trials can inspire the sort of alternative turbulence and cool confessionals that defined Exile -- and are the cornerstones of modern rock -- rest assured that Phair feels as whacked out in the traditional family structure as she did playing the dating game. In other words, she's grown, but she hasn't changed.

"Yeah, there is a theme on this record about being a contributing member of society, but she still feeling that rebelliousness underneath," Phair explains in a telephone interview in advance of her sold-out appearance with her band this Tuesday at Avalon. "In a way I'm in revolt against the very things I'm espousing. I see that ambiguity on the record -- wanting, now, 'to pitch in, and wanting to find new ways to break out. I think your personality holds true throughout your life."

That sort of ripe reflection -- the willingness not only to look not only to look hard but to look back -- has conjured some surprising revelations for Phair, and for devotees of the potty-mouthed prom queen who said and did it all. "I always felt like I was carrying a false mantle: 'the indie girl'," says Phair. "With Exile it was all conceptual -- the art, the music. I was actually in rebellion against all those people with hardcore indie tastes. I was like, 'Does anyone like to dance?'"

That's a striking admission from an artist who built a reputation on unraveling, in the first person, the mysteries of meaningless sex. One wonders to what extent she participated in her so-called life at all. "It's hard to say," Phair admits. "I couldn't have written those songs if I hadn't lived the emotions, and been in circumstances that brought about those emotions. I also can't imagine just literally saying what happened to me. Sometimes I can be hyperbolic, or underplay, because that ends up feeling more true. To get somebody to experience what you experience you have to play with your medium. But really, I wasn't so much living life as I was plotting a life, and a career."

So that luminously unhinged time of life, that perfect, terrible rock 'n' roll moment, that turns out to be show business as usual? Not exactly, says Phair. "Reality and fantasy were interwoven. That's what songwriting is. I love to create. Odyeseus going to the island; it's a way to travel and live and grow my insides. It's a real hand-in-hand marriage." The irony, of course, is that while Guyville smacks hard of autobiography, the refined fictional scenarios and embellished production of whitechocolatespaceegg are the more fully realized portrait of Liz Phair. The business of growing up, which took her away from the business of music for four years, has ultimately led Phair to a deeper level of personal and artistic freedom of expression.

While that may not sound like a recipe for rock, Phair would argue (and a close listen to the record bears her out) that setting up house in the suburbs doesn't have to mean giving up on the spirit of rock 'n' roll. (For more on this see Patti Smith, Chrissie Hynde, Kim Gordon.) "In the industry they were afraid of what I was gonna do," Phair says with a laugh. "My manager really wanted me to work with Brad Wood, who produced both Guyville and Whipsmart and split production duties equally on this project with Phair and R.E.M. producer Scott Litt. "He thought I'd thrown out the baby with the bathwater, and begged me to listen to the old records. I'm so much better for having gone back, and bringing that stuff with me."

The clean, fleshed-out tunes on whitechocolatespaceegg do reveal a kinder, gentler Liz Phair. But the things we relished in that raunchy little rich girl -- her candor, originality, wit, and fearlessness -- remain intact. "Love is nothing, nothing, nothing like they say / You gotta pick up the pieces every day / And I thought 'Who's this guy?' / Would I lie / To make the day blur into the night?" she sings on "Love Is Nothing". Our hero's youthful fantasy of a loyal boyfriend is followed by the shockingly unremarkable reality of marriage -- a turn of events which is, in its own deceptively quiet way, the most mind-blowing epiphany of all. "It's a death in our love who has brought us here / It's a birth that has changed our lives / It's a place that I hope we'll be leaving soon / And I fear for the year in his eyes," she allows on "Go On Ahead", a truly Phair assessment of how terribly unsettling settling down can be.

"Once you have kids you look at the bigger picture. The finger-pointing seems pointless and shallow," Phair says. "And that's the way I've been turning -- looking at myself, pointing fingers almost back at myself, confronting myself more than other people on this record. I'm not working at staying tough and frosty."

Tantalizing as the old image was, the thawed-out Phair is far and away more interesting. The same can be said of Phair's music. And while her persona is no longer picture-imperfect, Phair has resurfaced in a rock scene that has grown, not unlike our hero, into something too broad for neat definitions. A world that has witnessed the convergence of riot grrrls and Lilith Fair is a place where chicks with guitars can be moms, and be sexy, sleep-deprived, satisfied (sort of), and rock, all at once. Now that's alternative.