Valentin is 8 years old and lives with his grandmother in a Buenos Aires apartment in 1967. We know it's 1967 because we observe a Catholic priest eulogizing Che Guevara as a great humanist leader while the church's wealthy parishioners walk out. We know it's Buenos Aires because no other city possesses that particular cosmopolitan grace and erotic charge. And we know Valentin is 8 because he tells us so, and because perhaps at no other age can a boy so thoroughly convince himself that he's an astronaut simply by affixing weights to his shoes and wearing two fire extinguishers on his back.

"Valentin," writer-director Alejandro Agresti's semi-autobiographical coming-of-age story, features a thoroughly winning performance by newcomer Rodrigo Noya in the title role. Knock-kneed and cross-eyed, when he gazes at the incomprehensible adults around him through his thick, oversize glasses, he resembles the grandmother in last year's animated fantasy "The Triplets of Belleville." Rodrigo is even more winsome and sympathetic than she was, and he not only manages to carry the film on his sturdy little shoulders but also turns what might have been an exercise in maudlin self-congratulation into a sweetly rueful triumph.

In a matter-of-fact voice-over, Valentin explains the circumstances of his life. His parents split up when he was small, and since then he's been living with his loving but irascible grandmother (played by the great Spanish actress Carmen Maura). Longing for a more conventional family, Valentin lives in near-constant anticipation of his father's visits, when he invariably brings home his latest girlfriend. Usually, these liaisons don't pan out, but when Valentin meets Leticia (Julieta Cardinali), that changes. They spend an enchanted day together -- eating pizza, confiding in one another on long walks -- and by the end of the date he's decided that she is to be his mother. It's clear that she's fallen for him, too, but in the intervening hours, Valentin has been a bit too honest about his father's hot temper and anti-Semitism, both of which repel her. Leticia pulls back from Valentin's dad, plunging the little boy into confusion and despair.

These sequences are difficult to bear, as are those when Valentin loses someone dear to him. But Agresti tempers the melodrama of "Valentin" with lots of understated humor, and when the movie reaches its modestly optimistic conclusion, it has become not the sad tale of an isolated little boy but a celebration of youthful resilience. No one is better suited for this than Rodrigo, who infuses his character with a touching combination of wisdom and naivete. He easily slips into the starring role, but he's also well supported by Maura (one of Pedro Almodovar's divas). "Valentin" is also graced with wonderful performances by Mex Urtizberea, as Valentin's piano-playing neighbor, and Agresti himself, as the little boy's handsome but cruel father.

It's precisely Valentin's ability to see his father as both lovable and deeply flawed that marks one of the movie's subtle emotional victories. Quietly, with pathos and tinges of melancholy humor, "Valentin" pays homage to the heroism of creating your own world when the one that's on offer breaks your heart.

Valentin (87 minutes, in Spanish with subtitles, at Cineplex Odeon Dupont Circle and Landmark Bethesda Row) is rated PG-13 for some thematic elements and language.

Rodrigo Noya is engaging and sympathetic as Valentin, a young boy in 1960s Buenos Aires longing for a conventional family to love.