The Outsiders depicts a group of lost boys — the orphaned Curtis brothers and their gang of “greasers” — visited by the wise-beyond-her years ingenue Cherry Valance (played by a young Diane Lane in Francis Ford Coppola’s 1983 film adaptation). Curiously, for such a female-centric segment of publishing, The Outsiders, like Harry Potter, that other game-changer of children’s literature, focuses on a male protagonist, while its female author initially obscured her gender. In the case of Hinton, this decision was encouraged by Velma Varner, her editor at Viking, who believed that using her given name (S.E. stands for Susan Eloise), would “throw some of the boy readers off.”

So was Hinton a 1960s Wendy, looking after some Peter Pan in a leather jacket? She has acknowledged that she borrowed from life: her first person narrator, Ponyboy, and his friends “were inspired by a true-life gang, the members of which were very dear to me.” Yet their world of drive-ins and drug stores, freight trains and churches, is strangely scrubbed of geographical specificity. This must be Hinton’s Tulsa, though she never says so explicitly. The climactic rumble with the Socs could take place on any vacant lot in any city. Yet the relationships between the members of their gang — the misinterpreted protectiveness of Darry to Pony, the fatal devotion of Dallas to Johnny, the simpatico of Soda and Steve — are intricate enough to justify a map.

Asked if she identified as a greaser in high school, Hinton responded, “I was born without the need-to-belong gene, the gene that says you have to be in a little group to feel secure.” Which is maybe just another way of saying that she was a natural born writer — human enough to feel for others, yet sufficiently comfortable with solitude to get the pages down. Her characters, by contrast, embody and implicitly understand the contradictory wages of group identity, its sorrowful stain and addictive comforts. Ponyboy bemoans the indignities of being a greaser — “I don’t want to be a hood, but even if I don’t steal things and mug people and get boozed up, I’m marked lousy” — but he also takes enormous pride in the style and ethos of greaserdom. On the run, and forced to cut and dye his hair, he is pained by the loss: “Our hair labeled us greasers… it was our trademark. The one thing we were proud of.” Though he is slight and out of shape, and seems destined for a beating, he engages in that climactic rumble without self-pity, without questioning whether or not he should take part. He is not a fighter; yet rumbling is who his brothers are, and, thus, who he is.

The struggle between individuality and the need to be accepted by the pack has since become a standard theme of the genre, as has the depiction of taboo subjects through the unfazed yet still unjaded eyes of youth. Hinton takes for granted that teens engage in vices — brawling, smoking, drinking, sex and teen pregnancy — which, from an adult point of view, would be treated either as scandal or fetish. The level of violence is pretty low by current standards, however, and we don’t get a graphic description of even a single, solitary kiss. (The pregnancy is never acknowledged as such, only alluded to as a reason Sodapop, the middle Curtis brother, may have to marry his girlfriend. Like many an unwed teenage mother of that era, Sandy, the character to whom those decisions most pertain, is kept off screen.)

The Outsiders is still challenged by conservative groups frequently enough to earn it a place on the American Library Association’s banned books list. The depictions of sexuality and violence are actually fairly tame, but what is threatening here is Ponyboy’s matter-of-factness. He acknowledges that his love of cigarettes may impair his track team activities, in the same manner an adult might allow that their evening indulgences interfere with their morning runs, but there is no hierarchical hand-wringing, nor prurient fascination, regarding the corruption of innocents. The book has a mature view of brawling and bloodshed as both too common to escape, yet fundamentally useless. These things are, Hinton seems to be saying. Kids experience them as much as adults do, and often more acutely. For adult readers, her treatment refuses to cloak such wrenching experiences in the language of the fantastical or faraway, the foreign or the long ago. For kids, she seems to say: Walk right in.

A scene from Francis Ford Coppola’s 1983 film adaptation of The Outsiders. S.E. Hinton’s source material contains “no hierarchical hand-wringing, nor prurient fascination, regarding the corruption of innocents.” (Getty Images)

On the 40th anniversary of The Outsiders, the book critic Dale Peck pointed out in The New York Times that Hinton, like any writer learning on the job, absorbed her literary influences in a way that showed, “borrowing” from high and low, from Moby-Dick to The Sound of Music. He argues that this technique softens her debut’s subversive qualities but enhances its power as a work of art.

Hinton does rely on cliché quite a bit (a frightened character is “White as a ghost”; under attack, Ponyboy stands “like a bump on a log”), which may be literary inexperience, or maybe not. In any case it works, in Ponyboy’s voice, and the generic phrasing does nothing to detract from the sense of menace. He gives a rundown of his world’s vocabulary and rules of engagement early (“Greasers are almost like hoods; we steal things and drive old souped-up cars,”; “Tough and tuff are two different words. Tough is the same as rough; tuff means cool, sharp”) and moves on to the meat of the story: the bonds between vulnerable young people, and the chance for redemption in an unforgiving environment. With material that strong, linguistic bravura could only get in the way.

That blankness of tone is ultimately what makes The Outsiders a work of young adult fiction, and not simply a novel with a juvenile protagonist. I mean this as a high compliment, by the way — when I tried to read Catcher in the Rye as a teenager, I had the nauseating sense that I was being force-fed some other generation’s madness, some other generation’s solace and myth. What is so pleasurable about Hinton’s book is its openness to interpretation. Any reader can enjoy the superficial details that separate the warring tribes here — the long-haired hoods and the madras-wearing, clean cut rich kids — while still being able to project their own experiences along the have-and-have-not divide. There is just enough leather and fighting with broken bottles to give you a hit of postwar American cool, but not too much to interfere with a healthy sense of Je Suis Ponyboy.

Even when she stepped in it on Twitter, in October of last year — by arguing with a teenager’s interpretation of Dallas and Johnny’s relationship as homoerotic — Hinton ended up sounding like the tough and knowing den mother of outsiders everywhere. “Young gay kids can identify with the book without me saying the characters are gay,” Hinton tweeted. “I never set out to make anyone feel safe.”