Although the sparse design (by the band's Brooke Sietinsons) accurately reflects the album's enigmatic tenor, there's more than a minimalist aesthetic at work. "It's definitely a calculated move," says Greg Weeks, who sings and plays at least some of the listed guitars and keyboards. "It's like, look, it doesn't matter to us who's playing what, or who knows it. Anybody who knows the band knows there are delineated roles, but it's just not important. We really felt strongly that it should be designed without any kind of accent on any one individual."

THIS IS THE FOREST PRIMEVAL: Espers II was a group effort.

Given that Weeks was already established as a solo artist when Espers, initially a trio with Sietinsons and Meg Baird, formed in 2002, and that he produced both of the group's albums, it would be natural to assume that he runs the show. Indeed, Weeks likens his role to that of a director on a film set. "Directors have a long habit of getting performances from people by being aggressive, forcing them into situations that get things a little raw, and I personally feel like pushing people—not in any aggressive or violent way, but a creative goosing."

But when the opportunity arises for Weeks to take credit for his work, he grows suddenly circumspect. "We're in a band, and we're all in this together, making the same sacrifices to get to the same place." Putting one person over another "just doesn't seem right."

Weeks practically ties himself in knots avoiding the question of who writes the band's songs. "For the first record, the majority of tunes were written by two folks, and for this record two people also wrote the majority of the tunes," he says. "But it's not necessarily the same two people." Weeks and Baird do most of the singing, and a good chunk of the writing as well, but both say that the process of working out the songs with the full band alters them enough to merit collective writing credit—and, more tangibly, a six-way split of publishing royalties. "You could just come to the group with very sketchy songs, knowing they would take on life once they were arranged," Baird says.

Oddly, both Baird and Weeks say the initial writing process for Espers II was actually less of a group project than on the band's first album (titled, of course, Espers). But Baird says that the current lineup has been playing together long enough that it's almost possible to collaborate with them even when they're not around. "We have each other in our ears right now," she says. "Where the first time around, that wouldn't have been as easy to conjure up."

In addition to Weeks, Baird and Sietinsons, Espers' full contingent includes cellist Helena Espvall, bassist Chris Smith and drummer Otto Hauser, who also take up other instruments when the occasion warrants. The impact of the expanded lineup is apparent on the new album's "Widow's Weed," which weaves its way through several minutes of gnarled, snarling drone before resolving into a delicate, finger-picked lament. The medieval lilt that earned the first album comparisons to such forebears as Pentangle and The Incredible String Band (as well as headlines like "Faeries From Yon Philly Wood Revive Ye Olde Jousting Folke,") is still part of the mix, but Espers II is a more chaotic beast than its predecessor, a roiling sea from which fragile harmonies emerge and are swallowed up again.

The folk tag isn't inaccurate, exactly, but it says more about where the band are coming from than where they're going. Baird and her sister Laura (who lends flute to some Espers recordings), play traditional-sounding folk in The Baird Sisters, and their great-granduncle, I.G. Greer, was a North Carolina song collector. But Weeks, who harbors a fervent love of Italian progressive rock, says they were just as well-received when they toured with Stereolab as on a run of dates with The Incredible String Band. "Their fans were quiet, respectful, open-minded," he says. "It was kind of an overwhelming success." That the band is as comfortable with post-punk as pre-industrial music was demonstrated by last year's Weed Tree EP, which includes Durutti Column and Blue Öyster Cult covers alongside folk mainstays like "Black Is the Color," and throws in an Espers original for good measure.

"We're incorporating a lot of this earthy, human music, which is something a lot of people are interested in and responding to at the moment," Weeks says. "But it comes out of everything we've listened to our whole lives, and certainly psychedelic folk was not something that was on the turntable for all of us until recently. I like to consider it political in a way, because it's kind of a product of people moving in a certain direction, and that direction is more away from certain things than it is towards any one specific thing. Music is a reflection of what we're looking to escape from, and get to, in our own lives."

Espers will play Sun., June 25, 8 p.m., $10, with Brightblack Morning Light and Marie Sioux, First Unitarian Church, 22nd and Chestnut sts., 866-468-7619, www.r5productions.com.