Full Moon Fever is another rewarding, low-key side project for Petty. Produced by fellow Wilbury Jeff Lynne, the record is technically Petty's first solo outing, though all the Heartbreakers except for drummer Stan Lynch make an appearance. What's more, all the Wilburys save one (Bob Dylan) also show up: Full Moon Fever has the same restless charm and barbed wit as the Wilburys' LP.

Although Petty and Heartbreaker guitarist-songwriter Mike Campbell earn coproduction credits on the album, it is Lynne who holds sway. The former Electric Light Orchestra leader's production technique often builds banks of keyboards and backing vocals so high it's hard to see the song behind them, but on Full Moon Fever there are few of his characteristic excesses. In fact, the broader sound that Lynne brings to these twelve songs (most written by Petty and Lynne) usually fills them out without cluttering them. On songs like the brooding, deliberate rocker "I Won't Back Down," Lynne adds his trademark layers with a slightly lighter touch than usual; only on the grand-sounding "Love Is a Long Road" do the synthesizers and extra vocals beef up an arrangement with fat instead of muscle.

The opening song, the delicate "Free Fallin'," is not only the standout on Full Moon Fever but also one of the most concise, well-rounded performances of Petty's career. Over a spiral of acoustic guitars, Petty sings the tale of an abandoning lover. His story is full of internal inconsistencies - if he doesn't miss her, why is the whole first verse about her? - that serve to underline the character's misgivings. "I'm free!" Petty cries as he barges into the chorus, holding out some redemption for his narrator. But after a pause, he delivers the dark punch line: He's not free, he's merely "free fallin'." Although Lynne's smooth backing vocals cushion Petty as much as they can, this is one story that holds no happy landing.

"Free Fallin' " isn't the only high point on this sprawling album. The hell-bent "Runnin' Down a Dream," which offers a bruising solo by Campbell, suggests that Petty picked something up from touring with the ferocious Georgia Satellites, and "A Mind With a Heart of Its Own," a pop variation on the Bo Diddley beat, offers up offhand verses absurd and unexpected enough to make even Dylan smile. The barbs reach their peak on "Yer So Bad," which burps up a hilariously understated opening couplet ("My sister got lucky/Married a yuppie"); it's a track that could have fit on Beatles '65. "The Apartment Song" - more folk rock, but with a Chuck Berry edge - also engages in some nostalgia, with a drum break swiped wholesale from Buddy Holly's "Peggy Sue."

Although Full Moon Fever doesn't sound like a Petty-with-the-Heartbreakers record, there is much on the album to please longtime Petty fans. The chorus of "Depending on You," with its cascading guitar and keyboard parts, is the most overtly Heartbreaker-like, and the hard-earned lullaby "Alright for Now" recalls "It'll All Work Out," from Let Me Up (I've Had Enough).

The most inexplicable track is a note-for-note cover of the Byrds' "Feel a Whole Lot Better" that's all too obvious - Petty's voice has always been a ringer for Roger McGuinn's, and this song is the clear antecedent to Petty's "Listen to Her Heart." But Petty's just-as-obvious love for the song steamrolls over most objections.

The whole point of Full Moon Fever, however, is that it makes room for something like "Feel a Whole Lot Better," which would never find a place on a Petty-Heartbreakers record. The album is a chance for Petty to explore, play and maybe fall on his face without having much at stake. After all, he's already at work on his next effort with the Heartbreakers. So even if Full Moon Fever isn't Petty's best record, it sure sounds like it was the most fun to make.