Look! Out in that field. Is it a choir? Is it a cult? No, it's the Polyphonic Spree -- the nearly 30-member rock group collective from Dallas that enjoys being photographed wearing full-length robes in natural settings, smiling. Their cultish appearance is a little off-putting at first. If you didn't know it was a band, you'd probably think any one of them wanted to perhaps sell you a book or take you to a meeting that would change their life for the better and could change yours, too! (Or that an ensemble dance number from a production of Godspell was about to start.) Anyway, plenty of bands spend years playing gigs that never draw 30 people into a room, so the Spree may be onto something. In any case, it's a band that never needs to be lonely.

Maybe all that healthy social interaction with each other is why the band's music is so unabashedly -- almost creepily, to those of us with more generally negative attitudes -- cheerful. A case in point is the group's oddly upbeat cover of Nirvana's angsty growler "Lithium," which, done in its original form, sounded like the audible, acrid issue of Kurt Cobain's famously tormented digestive system, all acid misery and bubbling pain. The Polyphonic Spree version, released on 2006's digital download-only Wait EP and its latest full-length, this year's The Fragile Army, is frantically happy; singsongy, speeded-up and filled out with complete orchestration. Happy-happy, joy-joy. They are literally happy because today they found their friends were in their heads -- none of Nirvana's angry, druggy sarcasm for them. One hometown reviewer pointed out that there is a logical read for the choice of how to play the song, and it's clever if it's true. The title psychoactive drug treats bipolar disorder, and if Nirvana sang it from the point of view of crippling depression, the Spree is coming entirely from mania -- hyperactive, invincible, unreasonable joy. Judging from the success of this relentlessly joyous band, the 21st century indie-pop landscape is ready for some good news.

The sprawling collection of musicians and singers was recruited by Tim DeLaughter in 2000, after the demise of his band Tripping Daisy. (DeLaughter's still vocally wistful about that defunct project, which fell apart after guitarist Wes Berggren's death -- The Fragile Army includes a Tripping Daisy cover.) The fluctuating lineup runs not less than 13 and not more than 28, to all accounts so far, with members singing choral arrangements and playing dual keyboards and organ, violin, pedal steel, a full brass section, standard rock instrumentation, harp and theremin for a sound that's been called chamber pop, operatic rock and symphonic choral rock -- all played for a transcendent effect that's as uplifting as a performance of Jesus Christ Superstar. Although the band's philosophy is very much creating one sound from many voices, DeLaughter, along with Julie Doyle and two former Tripping Daisy bandmates, leads the group musically and ideologically. They create a sound that's psychedelic, exuberant and soaring, like the sunshiny ensemble pop of '60s and '70s acts like the Fifth Dimension or the trippy glee that the Flaming Lips produce. It's high-energy and vaguely religious-sounding, both in the way that anything choral is and because of the unrelenting optimism of the songs. And the robes, apparently, came about because 28 musicians onstage all in their own street clothes were too distracting to the eye.

The Fragile Army, on TVT Records, is the follow-up to 2004's acclaimed debut Together We're Heavy, and while remaining sunny in sound, it takes on more serious subject matter lyrically and sartorially. The band has shed the robes for plain black military gear decorated with medals symbolizing goodwill: a heart, a red cross (an image DeLaughter describes as "radiating unity") and a gold pin with the band's name on it. They've also, at least a little bit, put aside nonspecific exhortations to peace, unity and feeling pleasant for tracks like the title one: a direct anti-Bush screed DeLaughter says was written right after watching the State of the Union address, with actual anger couched in the blissed-out tones. Politically, the Spree is in uniform and gearing up for the revolution, and musically -- on its third label in three full-length albums -- the new seriousness and focus shows as well. DeLaughter and Doyle sketched out the songs on The Fragile Army, then took them to a core of 16 band members to finish together and work out arrangements, bringing in David Bowie's pianist Mike Garson to play on the record. The tonal shift from feel-good peace chorus to militaristic love army is actually quite slight and unlikely to turn off fans, though Doyle sums up why it hardly matters anyway: "We're not a part of any scene," she says. "To be part of the Polyphonic Spree is the coolest thing, because there's so many of us that we're our own scene."