Little girls in the movies have come a long way, baby. In the beginning, there was Shirley Temple, adorable and precocious and curly-haired. Then came Elizabeth Taylor, adorable and precocious and brunette. Seventy years later, we have arrived at Dakota Fanning, adorable and precocious and blond.

That’s why it’s so refreshing to meet Amelia, an 8-year-old girl who is one of the stars of “Girls Rock!” The documentary, opening in the city today, introduces us to a brand new kind of young girl — or rather, a fairly typical young girl, but one who has rarely been celebrated in popular culture.

Amelia needs to scream loudly and often, and she also writes songs with searching lyrics such as “How do you tune a taco?” She plans to invent 14 — and only 14 — songs about her dog, Pippi. She is alternately bursting with confidence and collapsing with insecurity. She is obsessed with screeching, feedback-heavy rock music, and also with the betrayal of her treacherous former friend, Hannah. She thinks it’s very, very important that she hold her guitar over and behind her head as a song ends, and announces with pride, “I made up a new chord, and it’s called ‘minus 10,’ and it’s very hard. It’s not even on the fret board.” Amelia is not “quirky” with the edges sanded off; she is weird — and it’s a blast of goofy pleasure to see her on the big screen.

Directed by first-timers Shane King and Arne Johnson, “Girls Rock!” documents one week in the life of the Rock ‘n’ Roll Camp for Girls. Located in a former sewing machine factory in Portland, Ore., the camp welcomes girls between the ages of 8 and 18 for five days of intense rock ‘n’ roll training. Campers form bands on Day 1, write songs together, and perform for a cheering audience of about 750 fans (okay, mostly family members) on the last day of camp. In between, they take self-defense workshops, participate in Robert Bly-worthy screaming exercises, and talk about girlhood.

The mood at camp is do-it-yourself and extremely positive; it’s about cooperation, joy, and similarly girly pursuits. Campers are aided by cool-girl counselors including former Sleater-Kinney guitarist Carrie Brownstein and Gossip frontwoman Beth Ditto. (The soundtrack includes songs by such outfits Le Tigre, Bikini Kill, Veruca Salt, and other powerful “girl” bands.) When the fierce, long-haired Portland rocker LKN performs, one camper exclaims, “She’s crazy, she snarls, she sings, she growls. She’s a total role model!”

True to this rebel spirit, Messrs. King and Johnson have avoided choosing the obvious cutie-pie subjects to focus on. Along with Amelia, the directors spend most of their time on three other girls. Misty, a teenage former meth addict, arrives at camp from a group home after spending almost a year in lockdown rehab. Cherubic Palace, 8, warbles, “San Francisco sucks sometimes; go to hell on the Golden Gate Bridge,” and can produce a primal scream to die for.

Viewers at first will cringe in recognition of 15-year-old Laura. Born in Korea and adopted as a baby by a couple in Oklahoma City, she’s an extroverted, self-professed libertarian who loves death metal and bunnies. Okay, maybe she’s not entirely recognizable, but her behavior is devastatingly familiar. Laura is so desperately eager to connect with other girls that as a consequence, she has terrific trouble doing so. She arrives at camp having been turned away from joining student bands at her school. She attributes this to being a girl, but most viewers will blame it on her unmistakable strangeness. She is the kind of girl high-schoolers are wired to reject. During early exercises at camp, it’s painful to watch her consistently fail to find a partner and be turned away from various bands as they form. Yes, even here there are mean girls.

By the final concert, however, Laura has found her voice, embracing rather than tempering her hyperactive essence. She bops around the stage, singing, “I’m not ashamed of what I am, a woman can rock as hard as man … You hate me so much, I guess that’s true. I guess I rock a lot harder than you!” She feels welcomed, too. “To have people think that you’re interesting, not ‘interesting,'” she says, “that’s pretty cool.” Those are very wise words, and a worthy ideal for anyone who sees himself or herself as an oddball: Find the people who think you’re interesting.

It should be noted that the film’s narrative is a bit shaggy, and the drama low-stakes. The opening voice-over asks, “Will the young rockers find enough power within themselves to reclaim girl culture in time?” Spoiler alert: Yes, they will. Other burning questions: Will Hip-Hop Anonymous change its band name? Will Palace apologize for punching Annemarie in the face? It’s hard to get too invested in these questions, but you can’t fault the filmmakers for trying.

In several peppy animated montages, the directors also attempt to inject drama by making a haphazard case for the essential trauma of experiencing girlhood in America. In these segments,” Girls Rock!” becomes a sort of “Reviving Ophelia” for the punk-rock set. Girls are dieting and watching MTV at ever-younger ages. Twice as many boys as girls identify their talents as what they’re most proud of in themselves; girls tend to name a body part as their best feature. One sequence cites the 1994 book “Failing at Fairness: How America’s Schools Cheat Girls” with the assertion, “Girls are the only group in society that starts school with a testing advantage and leaves with a disadvantage.” But Christina Hoff Sommers and others have persuasively argued that it’s boys who are struggling: They typically earn lower grades, are less engaged academically, and lag behind women in college enrollment.

So there’s bad news for everyone. Ah, well. “Girls Rock!” is stronger when it’s showing us real girls happily rocking out than when it’s making the case that girlhood is harsher than boyhood. Maybe it is. But the more complicated truth is that adolescence is harsh, especially for those who will later turn out to be interesting.

Still, it’s a pure jolt of girl-power pleasure to see campers revel in, as one counselor puts it, this “place where you can take up space.” Rock ‘n’ Roll Camp is a too-rare haven where young girls don’t have to apologize for having extra opinions, extra pounds, or an extra-large voice, and where they don’t have to seem demurely adorable and precocious. Here, girls are stars, not cheerleaders. As Laura points out, after complaining that many of her peers at home brag about hanging out with musicians, “Why don’t you start your own band, supergenius? That’s a lot cooler than having a boyfriend in a band.” Rock on.

Ms. Graham is an editor at Domino magazine.