The documentary “Teenage” uses archival footage and some freshly shot scenes that have been filtered to fit in with the tumultuous times. (Oscilloscope Laboratories)

It’s hard to believe that not so long ago, the word teenager did not exist. Western culture has been so aggressively youth-driven for so many decades — way before Gossip Girls even gossiped, you guys — that it’s inconceivable to think that, in the earliest days of the 20th century, there was no socially acknowledged stage between childhood and adulthood. Back in the early 1900s, you were a kid, then you started working for a living and became a grown-up, and that was pretty much it. There was no middle ground and no time to indulge in rebelling, with or without causes.

In “Teenage,” director Matt Wolf evocatively explores how all of that changed between 1904, when stricter child labor laws became the norm, and 1945, the year World War II ended and the New York Times published a “Teen-Age Bill of Rights” that established, among other things, that a young man possesses “the right to a ‘say’ about his own life.”

Taking a refreshingly impressionistic approach to the documentary form, Wolf traces the evolution of the teenager from non-entity into a force for social and cultural change, a role that sometimes involved unbridled, boundary-pushing fun (see England’s bright young things in the 1920s or the swing music craze born in the 1930s) and sometimes was exploited to spread propaganda that proved dangerous to the entire world. “Slowly, you lost yourself,” says a female narrator representing the voice of a member of the Hitler Youth, just before the screen fills with a crowd of young Nazis all saluting like a sea of overexcited fans at a pop concert. “Teenage” is full of moments like that, powerful illustrations of the double-edged nature of being young, impressionable and capable of kickstarting a revolution.

Wolf — who wrote “Teenage” with Jon Savage, author of “Teenage: The Creation of Youth Culture 1875-1945” — deftly weaves together various media in a way that breathes its own youthful, stream-of-conscious life into the documentary genre. The filmmaker fuses archival motion pictures and stills; scripted as well as non-scripted recollections from teens of the time, as recorded by actors Ben Whishaw, Jena Malone and others; and newly shot material that’s overexposed or infused with sepia tones so that it blends seamlessly with the older footage. The result is an oral history that moves, a series of personal recollections about the key moments in the ascendance of youth culture that unfolds like a teenage dream.

As admirable as Wolf’s free-flowing approach may be, there are times when adding more context to explain some of the events would be helpful. As a document of the decades it covers, the movie does more skimming than deep diving into its subjects. Some post-screening Googling and Wikipedia-ing may be in order for those who want to know more about, say, the sexist attitudes lobbed at World War II’s so-called victory girls, or what really happened during the Los Angeles zoot suit riots in 1943.

But as a film attempting to capture the hormonal forces at war within every teen and how they eventually spill over into the culture at large, “Teenage” succeeds with every successive close-up of another high schooler whose eyes look directly into camera with that distinctly adolescent blend of hope, fear and defiance. Some of those faces may have been photographed 80 years ago or more, but their expressions are no different from the ones worn by the teens of 2014, who, just like their ancestors, believe that the world is speedy and that the only ones capable of keeping up are the vibrant and the young.

Chaney is a freelance writer.

★ ★ ½

Unrated. At Landmark’s E Street Cinema. Contains nudity. 78 minutes.