There’s no “there” there in “Teenage,” a meandering mess of a documentary that has the feel of a bloated, inchoate term paper.

Inspired by a 2007 non­fiction book by Jon Savage, “Teenage” purports to track the emergence of “adolescence” during the 20th century — as a concept, sociocultural phenomenon and consumer group.

Sounds good, but filmmaker Matt Wolf quickly bites off more than he can chew while, paradoxically, shortchanging his purpose. Wolf concentrates on the vicissitudes of youth in America, England and Germany during turbulent years, though why only those countries is not clear.

Also, by the time Wolf arrives at the thematically fertile, post-World War II era, when teenagers became a truly potent, self-referential force, “Teenage” is practically over, reduced to a dizzying whirl of impressionistic images.

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“Teenage” is comprised entirely of archival footage and pictures, with narration read by actors Jena Malone and Ben Whishaw, among others. Well, not quite “entirely”: Wolf slips in original passages made to look as vintage as the real, dusted-off visual materials.

The problem with many of those older materials is that they are confusing in this context. The people seen in still photos or black-and-white clips are often not teens at all but rather young adults or pre-adolescents.

When Wolf tells us Germany sent many boys into battle toward the end of World War II, the visual evidence is that he’s talking about kids around 12. When he turns his attention to a British flapper who was all the rage at age 19 in 1926, he’s drifting from a literal notion of adolescence.

Wolf does score points for his quick overview of evolving child-labor laws and, especially, his dissection of the Hitler Youth experience.

“Teenage” would have benefited from a narrower focus where Wolf could have dug in rather than drown in grandiosity.

Tom Keogh: