For nearly 17 years, Yonder Mountain String Band has redefined bluegrass music, expanding the traditional acoustic genre beyond its previously established boundaries by steadily pushing the envelope into the realms of rock 'n' roll and improvisation.

The band will bring its unique style to Penn's Peak at 8 p.m. June 26.With its latest album, "Black Sheep," Yonder Mountain String Band - Adam Aijala (guitar, vocals), Dave Johnston (banjo, vocals), Ben Kaufmann (bass, vocals), Allie Kral (violin, vocals) and Jacob Jolliff (mandolin, vocals) - begins a new era. The first YMSB release produced by the band itself, "Black Sheep" is, by any measure, a triumph."This record sounds more like Yonder than any record we've ever done," says Kaufmann. "I'm hoping that when people are finished listening to it, they'll just hit play and listen to it again.""Black Sheep" marks the first time in Yonder's history that they're actually utilizing, throughout an entire record, the conventional five-piece instrumental arsenal of bluegrass introduced in the 1940s: guitar, mandolin, banjo, fiddle and bass.With the exception of the album's sole cover tune, "Ever Fallen in Love," originally by the late '70s British punk-rock band the Buzzcocks, each of the album's new tracks were written by the YMSB members.Yonder has its roots in the year 1998, when the original quartet came together in Colorado. Through steadfast gigging in all manner of venues from small clubs to massive outdoor festivals, Yonder Mountain String Band quickly built a robust fan base while continually experimenting to define its sound.Some of the most fervent audiences were at jam band shows and festivals, where fans took readily to YMSB's potent mix of the traditional bluegrass of Bill Monroe, the Stanley Brothers and Doc Watson, and the improvisational sensibilities of the Grateful Dead and Phish.Also deeply ingrained in the band, albeit more subtly, was a fierce love for punk, which provided the members with seminal influences while they were growing up."We didn't even hear bluegrass until our 20s," says Aijala. "Falling in love with the sound of bluegrass instruments, while also having all of these outside influences that had nothing to do with bluegrass - well, what comes out isn't what we envisioned."With the band's 17th anniversary coming up, and an extensive tour schedule running throughout the year, a revitalized Yonder Mountain takes delight in the fact that it is still reaching new fans while simultaneously retaining the characteristics that brought their greater community together in the first place."We've been growing over the years and I feel like we really don't have any limitations," says Aijala. "It doesn't feel like work when you get to hang out with people that you care about and play music."Also at Penn's Peak• June 17, Average White Band, 8 p.m.• June 18, Kix with Autograph, 8 p.m.• June 23, Happy Together Tour, 8 p.m.• June 24, Joan Jett & the Blackhearts, 8 p.m.• June 25, Hotel California, A Salute to the Eagles, 8 p.m.• June 26, Yonder Mountain String Band, 8 p.m.• July 1, The Yardbirds, 8 p.m.• July 9, Mark Farner, formerly of Grand Funk Railroad, 8 p.m.• July 15, Back to the Eighties Show with Jesse's Girl, 8 p.m.• July 16, Lonestar, 8 p.m.• July 21, Old Crow Medicine Show, 8 p.m.• July 29, Blues Traveler, 8 p.m.• July 30, Ricky Skaggs and Kentucky Thunder, 8 p.m.• Aug. 24, Ted Nugent, 8 p.m.• Sept. 9, Bruce Hornsby and the Noisemakers, 8 p.m.• Sept. 29, Trace Adkins, 8 p.m.• Sept. 30, Jim Breuer, 8 p.m.• Oct. 21, Jethro Tull's Martin Barre, 8 p.m.Tickets are available at all Ticketmaster outlets, the Penn's Peak Box Office and Roadies Restaurant and Bar. For more information, go to

www.pennspeak.com or call 866-605-7325.