"Tex," a heartening little gem of a movie, depicts adolescent unrest and confusion in sanely affirmative terms. It reinforces personal and social values without getting sanctimonious.

A likable human-interest story, it deals with the problems encountered by a pair of teen-age brothers whose father, a rodeo bum, neglects them when he is out on the circuit.

Mason and Tex McCormack are attractively played by Jim Metzler and Matt Dillon. The publishers of fan magazines aimed at teenyboppers testify that Dillon is Heartthrob Numero Uno with their readers. The role of Tex, a real sweetheart of a kid, ought to have those readers lining up at movie theaters. In the dominant role of the older brother, Metzler makes an impression that should evoke similar emotions, romantic or sisterly or maternal, in a slightly older crowd, say, all female moviegoers above the age of consent.

"Tex" blends the appealing elements of films like "Hud" and "Breaking Away." It also represents a grittier, more subtle, down-home exploration of the same general subject -- adolescent growing pains--that appears to be charming suburban American audiences in the curiously exotic, soft-textured form presented by the Scottish import "Gregory's Girl."

The screenplay, written by Tim Hunter (who also directed) and Charlie Haas, is based on a 1979 novella by Tulsa's S.E. Hinton, and the writers demonstrate an ability to achieve an unusual sense of proportion for movies dealing with teen-agers in jams.

Given these apparently winning commercial attributes, it's impossible to account for the discouraging fact that "Tex" opened to meager business in a number of southern and southwestern markets last July. Evidently, the film held its own only in the Tulsa area. Stunned and alarmed, the Disney studio, which really deserves congratulations for rejuvenating its approach to filmmaking with a picture like "Tex," felt obliged to pull it from release. Now the company hopes to salvage things with a careful, prestige release in the North, following a successful showing at the New York Film Festival.

Still, considering the success of facetious junk like "Porky's," "Tex" may be at a competitive disadvantage because it depicts adolescent experience realistically. This straightforward, levelheaded outlook seems like a welcome novelty, but it may disappoint young viewers who'd prefer to see a distorted, ribald image of themselves.

For example, "Tex" is so uncompromisingly realistic about what kids can expect out of life that it dares to suggest that they really can't expect much in the way of sexual gratification. Tex is stopped in his amorous tracks during an exploratory necking session with the girl he likes, Jamie Collins, smartly played by a mischievous-looking young actress named Meg Tilly, and she's got good reasons for putting him off. When Tex describes his lack of success to brother Mason, expecting a few pointers from the Voice of Experience, he's shocked to learn an awful but convincing secret: Mason isn't getting any action either.

This type of comic deflation rings true, but will it cost the movie to keep ringing notes that tend to be true to life? In a certain respect both Hinton and the filmmakers might be faulted for misleading the audience, because the plot is riddled with melodramatic episodes, beginning with the fraternal punch-out that occurs when Mason informs Tex that he's sold their horses without bothering to consult his kid brother. It's this betrayal that fuels a simmering resentment in Tex and keeps the basically devoted brothers in an edgy state of psychological conflict and misunderstanding until the denouement. The break is healed with a reconciliation that's at once touching and wittily contrived.

Along the way there are incidents that suggest that Jamie's wealthy, disapproving father Cole (Ben Johnson in a scold's role that really won't do) will cause trouble for the McCormack boys, that Mason is driving himself toward a serious illness, that the boys will end up the victims of a killer on the loose, that Tex might let his angry impulses carry him over the edge into delinquency and even criminality.

Nothing catastrophic does follow, and Hunter has such a dry, casual touch that the melodrama doesn't impose a false sense of urgency anyway. This equanimity keeps potentially runaway episodes from running wild. Instead, one feels that the material is adding up methodically in an emotional sense, concentrating on the process that ultimately matters -- Tex's maturation.

Dillon presents such an open, unguarded countenance to the camera that Tex's accumulation of self-knowledge and self-respect becomes an unusually visible process. You're persuaded that you can actually see this particular ignorant kid wising up over the course of the story, and acquiring the degree of wisdom he does in the circumstances life has dealt him seems a stirring, heroic achievement.

Metzler is astute enough to prevent Mason from degenerating into a heroic masochist. The smartness, pride and resourcefulness that make him seem so capable and admirable in many respects also have a creepy side, because his determination to take charge of things in the absence of his father creates behavioral strains. He's driving himself so relentlessly that he's becoming embittered and self-righteous. He needs to have this unnatural burden of adult responsibility lifted as much as Tex needs to put certain juvenile impulses behind him.

When the brothers finally confront each other on an equal footing at the conclusion, it's an exalted sentimental moment, but Hunter's uncanny discretion doesn't fail him. Sweet as it is, he doesn't permit this reconciliation to linger on the screen a second too long. Maybe that's why it's certain to linger in your memory.