For her first public performance in several years, Joni Mitchell found a way to affirm her spiritual ties to the folk music community whence she came, while showcasing songs whose intentions ranged far beyond that music's traditional boundaries. The occasion was a two-day "Troubadours of Folk" festival in the open air of UCLA's Drake Stadium, featuring an impressive lineup of '60s-generation acoustic warriors (John Prine, Roger McGuinn, Judy Collins, Arlo Guthrie, Richie Havens, et cetera) and a middle-aging audience similarly uncertain whether such gatherings symbolized nostalgia or renewal. Most seemed content to let the matter ride and have a good time.

But when Mitchell finally appeared toting her guitar, the crowd in front of the stage became palpably attentive - this, after all, was an event - while several of the day's other performers formed a thick crescent around the stage rear. As if sensing a collective hunger for Something Different, she launched an unfamiliar composition, "Last Chance Lost," by bending long phrases around the languid, jazz-inflected melody in a way that brought to mind Betty Carter - a sultry sound masking spiky sentiment. Next up was a slower, chunkier version of "Big Yellow Taxi" the song's original whimsy perhaps flattened by two decades' worth of witnessing its truths-and a wistful "Amelia," its succession of visual images seeming to hover and then dissolve like Mitchell's frosted breath in the cool evening air.

Technically, the show was far from perfect. The years have ripened her voice into a rich, dusky instrument as commanding as her personality, and heavy-stroked guitar rhythms provided a sturdy, propulsive bottom for Mitchell's intricate compositions. But on this night she was clearly nervous - just before she went on, you could see her puffing cancer sticks in the wings - and almost every song was saddled with a false start, missed chords or some such glitch. "I gotta practice more," she chided herself at one point, and you got the idea she wasn't kidding.

All of which could have been a recipe for disaster in front of a less supportive crowd - anyone remember Amnesty International? Instead, Mitchell's wit and disarming candor transformed this into an event of uncommon charm. At one point, she forgot the words to "Hejira" and had to stop in mid-song and ask the front-row listeners to prompt her memory. They did. Sobering new songs like "Sunny Sunday" - "about a woman waiting for a break," as she put it - and "Borderlines," a kind of kaddish for a culture that keeps ripping its own seams apart, were received warmly. By the time she closed with "Night Ride Home," the rapport between singer and audience seemed to mirror that song's hard-won serenity.

"Thank you very much," she said before exiting. "You've been wonderful, wonderful, wonderful!" Lawrence Welk couldn't have put it any better.