It takes some gumption to watch a movie that could easily amount to 91 minutes of young girls screaming. Which is why Girls Rock! seems so daunting at first. The film documents Portland's Rock 'n' Roll Camp for Girls, a much lauded music-based retreat aimed at teaching young women self-confidence, DIY ethics and teamwork through the basics of rock. An admirable undertaking to be sure, but that doesn't mean watching it will be fun.

Girls form bands and write songs over five days of camp (which is interspersed with everything from self-defense classes to good old-fashioned arts and crafts), all in preparation for a showcase at the Wonder Ballroom. Despite cringe-worthy moments—like a shrieking "I say, 'Girls!' You say, 'Rock!'" chant-along led by the Gossip's Beth Ditto—the movie itself succeeds on a number of levels. And it doesn't take long to see that Girls Rock!, and the camp itself (which welcomes girls ages 8 to 18), isn't so much about making noise: It's about believing in and being comfortable with yourself, albeit through the power of making noise. As former assistant director Jen Agosta says: "Our whole program is about that, it's just music is our medium."

Directed by Portlanders Arne Johnson and Shane King, Girls Rock! makes the camp's mission clear right off the bat, then quickly delves into what matters most: the campers. The film specifically focuses on the experiences of four young women: eccentric 8-year-old Amelia; troubled, parentless 17-year-old Misty; 15-year-old Korean death-metal fan Laura; and 7-year-old pretty-girl Palace. Their individual transformations (or lack thereof) are both telling and, lucky for the movie, entertaining.

Through each girl's individual band practices—which are fraught with trials from band-name disputes and violent lashings-out (Palace punches one of her bandmates out of frustration and writes a song about burning down San Francisco) to genre-identity issues—the viewer sees how much the camp has to offer those who are willing to learn and grow.

Early on, Laura, a self-conscious adoptee who has little voice in her male-fronted band, Thief, says assuredly, "It's cooler to be in a band than to date someone in a band." Misty, who has a history of drug abuse and gang activity, realizes she has something to say when, one day at practice, lyrics come pouring out of her. Even Palace, who'll undoubtedly charm viewers with her rebel yell ("Are you ready to rock, Portland, Oregon?"), has to deal with the aftermath of her own rage. (Though, truth be told, the amazingly self-aware little girl seems more concerned with amending her social status than sincerely sorry.)

It's Amelia, though, who adds a dose of reality to Girls Rock! An attention hog of the worst sort, Amelia wails in practice while her bandmates rest their heads on their instruments and sigh. Her group's counselor offers wise words on teamwork, but to no avail. The toothy-grinned, red-spectacled guitarist plans to pen a 14-song cycle about her dog, Pippi, and claims, "I'm not somebody like Hilary Duff, who just wants to be famous." But she doesn't take much action to the contrary. When the showcase comes around, her band (P.L.A.I.D.: People Lying Around In Dirt) plays a disastrous set. It's not a disaster because it sounds bad (which it does), but because there's no cooperation in sight. You just feel annoyed with Amelia and sorry for her bandmates.

That said, the camp's counselors—who range from veritable superstars like Ditto and Sleater-Kinney guitarist Carrie Brownstein to local electric guitar virtuoso LKN (the soundtrack, likewise, is chock-full of apt tunes such as Bikini Kill's "Rebel Girl" and Veruca Salt's "Volcano Girl")—do their damnedest to help these girls discover their potential. Sometimes it works; sometimes it doesn't. But perhaps that's why Girls Rock! succeeds as a documentary; instead of delivering a fantasy transformation amid stats on eating disorders and women's self-image (which do abound), it feels real. And, because kids like Laura realize, often for the first time, that they're truly interesting (not distastefully "interesting," as she says), it's ultimately inspiring.

Girls Rock!

is rated PG. It opens Friday, March 7, at Cinema 21.