Mason (Ellar Coltrane) at age 11, Samantha (Lorelei Linklater) and Mason Sr. (Ethan Hawke) in Richard Linklater’s “Boyhood.” (Courtesy of Matt Lankes)

Richard Linklater’s new movie, “Boyhood,” which arrives in theaters nationally today, follows a child from the age 6 to his first day of college. It is the result of a remarkable act of dedication. Linklater and his collaborators got together for a few days every year over the course of 12 years, capturing the real aging process not just of his star, Ellar Coltrane, who plays Mason Jr., but of the actors who play his parents and sister.

Coltrane gives an often wonderful performance, and Linklater captures and coaxes out boyish hand gestures of frustration and Mason’s tentative smiles when he starts classes at a new school or meets a cute girl.

You can see the moment that Mason becomes himself. The expression on Coltrane’s face when Mason is trying to get out of a sex talk his father (Ethan Hawke) is giving mostly to his sister (Lorelei Linklater) will appear again and again throughout the rest of the movie. In a film that eschews histrionics and exaggerated high stakes, Linklater’s eye for that sort of detail and Coltrane’s ability to carry it through Mason’s many haircuts and new schools is absolutely pivotal.

But even as the circumstances in which “Boyhood” was made are without clear precedent, Coltrane’s performance comes to us at a moment of incredible wealth of child and young adult acting. For all that we are swamped with anti-heroes and superheroes, film and television are also giving us rich stories about childhood and teenage years, anchored in tremendous performances by very young actors.

Part of what makes this moment so remarkable is the prior inexperience of the young actors who are giving us such wonderful performances. Coltrane had one movie credit to his name before Linklater cast him in “Boyhood.”

Quvenzhané Wallis had never acted before when she and her parents concealed her age so that she could audition for the lead role of Hushpuppy in “Beasts of the Southern Wild.” The film weaves together myth and climate change to explore the trauma left behind by a storm much like Hurricane Katrina, and Wallis gave a commanding performance in it. At age 9, she became the youngest person to earn an Academy Award nomination for best actress.

And Wes Anderson’s “Moonrise Kingdom” is so piercingly sad and brave precisely because of the freshness of its young stars, Jared Gilman and Kara Hayward, both of whom were performing in movies for the first time. They play Sam, who is open and hopeful, despite his failure to find a permanent foster home, and Suzy, whose  growing awareness of her own parents’ imperfections and hypocrisies has manifested as occasionally violent anger.

When the two run away together, their characters have every belief in the world that they can get married and begin their lives together, despite their tender ages. Gilman and Hayward are beautifully unencumbered by any sense of how fictional children are supposed to behave: They are alternately grave and unselfconscious.

In television, Maisie Williams and Sophie Turner, who give remarkable and remarkably different performances as sisters Arya and Sansa Stark in “Game of Thrones,” were both newcomers to film and television when HBO’s epic fantasy debuted in 2011. Isaac Hempstead-Wright, who plays their younger brother Bran, had only one prior credit to his name.

Keidrich Sellati, who plays Henry Jennings on FX’s Cold War spy drama “The Americans,” is also a newcomer. Ursula Parker, who plays the main character’s daughter on “Louie,” made her debut in that show and the movie “Rabbit Hole” in 2010.

In addition to spotting new talent, television in particular seems to be getting better at figuring out how to use and write for its younger characters. As is the case in “Boyhood,” these new heights come when children are allowed to be genuinely childlike, often in ways that confound their parents.

In “Boyhood,” Mason demands the truth about whether or not magic exists in a way that defies his father’s attempts to convince him that the world is still a mysterious and amazing place. “Right this second, there’s, like, no elves in the world?” Mason asks. “No,” his father tells him after a moment of consideration, “Technically no elves.”

Mason grows out of his wistful dreams of elves in “Boyhood,” but the world of “Beasts of the Southern Wild” is so fantastical that it sometimes seems like the product of Hushpuppy’s own imaginings.

“The Bathtub has more holidays than the whole rest of the world,” Hushpuppy tells us early in the movie. “Daddy’s always saying that up in the dry world, they ain’t got none of what we got. They only have holidays once a year. They got fish stuck in wrappers and babies stuck in carriages…Me and my daddy, we stay right here…We’s who the earth is for.”

This sense of her centrality in the world, her courage in comparison to everyone else around her, makes Hushpuppy a hero when the weather turns wild and the adults around her falter. She tears into a feast of crabs during a storm, leads an escape from a government-run medical center and, in the movie’s final moments, stares down a giant aurochs.

That sort of wild independence cannot last forever, of course. As children grow up, they must reconcile the wiles that seem so charming when they are young with the rules that govern adult behavior. Last season on “The Americans,” Henry breaks down into a flood of tears after he is caught sneaking into another family’s house to play with its sophisticated video gaming system.

“You don’t have to tell me. I know what you’re going to say,” Henry desperately tries to explain to his parents, punishing himself worse than they ever could. “It’s not like I haven’t been thinking about it nonstop. I have. It makes me sick. I feel like I’m going to throw up. But I didn’t take anything. I wouldn’t do that. And I didn’t hurt anybody. I know the difference between right and wrong. You know that, right?”

Holly Taylor, who plays Henry’s sister Paige sister on “The Americans,” and Makenzie Vega, who plays Grace Florrick, the younger daughter of a lawyer and politician on “The Good Wife,” are in a different position than Henry. Both girls are converts to Christianity, and their faith puts them at odds with their parents’ morality.

This season on “The Americans,” Paige, who Taylor plays with a great restraint that hints at the secret lives of teenage girls, got in trouble after donating her savings to her new church. It was an action that horrified  her parents who are not just atheists, but deep-cover KGB spies. “They’re saving refugees, building houses! You guys don’t help anyone,” Paige told her parents bitterly. She thought she was getting at her parents’ lack of charity. But her words actually deepened the crisis her father was experiencing about the often-brutal nature of his work as a Soviet agent.

And on “The Good Wife,” Grace served as a spiritual counselor to her mother (Julianna Margulies) after the murder of her mother’s former colleague and lover. “What does it mean if there is no God? Why is that any better?” Grace prodded her despairing mother gently. “Always believing the bad, maybe that’s wishful thinking too.” The scene is kinder than the confrontation on “The Americans,” but Vega’s performance captured both the pain and necessity of children’s pulling away from their parents.

This sort of childishness does not always have to lead to moral revelations, just to clear glimpses of what it is like to be young and bored or wounded. As Jane on “Louie,” Ursula Parker whines so consistently and magnificently that Vulture actually put together a supercut of her complaints.

Rewatching “Mad Men,” it is remarkable to see how early Sally (Kiernan Shipka) learns an expression of sour disappointment. No matter what her parents, the fickle housewife Betty (January Jones) and the reckless advertising Don (Jon Hamm), do to try to rectify the damage done by their divorce, those of us who watch her closely know that Sally was poisoned by their parenting even before their split. Shipka cultivates a flat tone to Sally’s voice that makes the breaks in her composure, often when she is fighting with her mother or running to her, even more dramatic.

Young characters, in other words, have gotten some of the same permission to be complicated people that has been extended to their elders. And young actors have taken full advantage of the parts that are being written for them, turning in performances of wonderful humor and melancholy.

It is no mistake that the careers of some young actresses hold out the promise that they could change the range of parts offered to adults, too.

Abigail Breslin and Chloë Grace Moretz played a range of strange little girls as children. Breslin was an unpolished aspiring pageant queen in “Little Miss Sunshine.” Moretz was Joseph Gordon-Levitt’s preternaturally wise younger sister in the indie romantic comedy “500 Days of Summer” and sparred with Alec Baldwin over control of a giant corporation in guest performances on “30 Rock.”

Now, like Shailene Woodley and Jennifer Lawrence, who anchor the “Divergent” and “Hunger Games” franchises respectively, and Hailee Steinfeld, who starred in “True Grit” and “Ender’s Game,” Breslin and Moretz are credentialing themselves as action stars. Moretz took a marvelous, demented Daddy’s Little Girl turn as in the dark superhero franchise “Kick-Ass.” Breslin has the lead role in the forthcoming action thriller “Final Girl,” which takes a swipe at horror movie tropes. The test for their industry will be whether filmmakers continue to respond to that potential and make similar roles available to them going forward.

Quvenzhané Wallis’s career poses a different kind of challenge for Hollywood. Wallis anchored “Beasts” with a combination of pure childishness and preternatural calm, and she followed that film up with a role in “12 Years a Slave” and the lead in a remake of “Annie,” due out later this year. Wallis has tremendous talent and charm, but hope for her future comes paired with anxiety about whether her appeal can help her carve out a full career in an industry that offers limited opportunities for black girls and women.

This is what it means to watch someone grow up. We tie our bright and beautiful hopes to young people, only to find that those dreams get abandoned on the playground or scuffed in play. But in the best conditions, those young people come up with dreams of their own, lovelier and braver than any we might have imagined for them.

We are lucky enough to go to the movies and watch television at a moment our screens are full of incredibly talented and very young actors. We can only hope that they build careers for themselves that are wild, wonderful and unexpected in a way that matches this moment of early promise.

Alyssa Rosenberg blogs about pop culture for The Washington Post's Opinions section.