Feel-good movies are on the whole predictable and mediocre, the ethnic variety even lower, and the up-with-people/teen brand almost by definition the pits. Branching into all three categories, Quinceañera overcomes preconceptions, however, and the only question is why, with major prizes at Sundance and already shown at the Lincoln Center-MoMA New Directors 2006, this winning feature is not being released before mid-August to catch the full summer grown-up family market.

Eschewing extremes of atmospheric pans and sports coverage close-ups and to be commended for the courage to picture an unlikable yuppie gay couple, the film is surprising in neither plot nor characterization. But from beginning to end, cowriters/-directors Richard Glatzer and Wash Westmoreland’s “reinvention of Kitchen Sink realism drama” is buoyed by the energy of its handheld eighteen-day location shoot “within one mile of our front door” and the feel of an unpretentious barrio, by the enthusiastic camera presence of non-professional locals, and by the true performances of fifteen-year-old first-timer Emily Ríos as Magdalena and young star in the making Jesse García in the rôle of Carlos.

The title is Spanish for both a fifteen-year-old girl and the usually church-related festivities marking her coming-of-age, combining aspects of traditional and modern in California Mexican communities’ equivalent of the bat mitzvah, cotillion, sweet sixteen and debutante ball. The story opens and closes with two cousins’ such dinner-jacket-and-strapless-gown ceremonies, which move from formal mariachi-and-organ-flavored “Fascination” waltz to teen reggaeton gyrations. Eileen (Alicia Sixtos) celebrates her special day, the formal religious part first at Echo Park’s Evangelical Church of God, where, backed by north woods wallpaper, her uncle Pastor Ernesto (Jesús Castaños-Chima) presides, “a good man, but his head in the clouds,” says wife María (Araceli Guzmán-Rico).

The only discordant note is the late, surly, reception hall appearance of pothead street tough Carlos, who comes bearing a stolen rose for his sister, is forcibly thrown out, and, disowned by their parents (Carmen Aguirre and Johnny Chávez, as Aunt Silvia and Uncle Walter), moves in with understanding great-great-uncle Tío Tomás (Peckinpah veteran Chalo González).

Dutiful but upset because her father Ernesto will not rent a Hummer limo for her own upcoming big day, and because snooty Aunt Silvia is going to alter Eileen’s gown for her to wear, Magdalena hangs out with school friends -- their giggly teentalk sessions on boys, makeup and clothes ring authentic -- and rides standing up on the back of the bicycle of boyfriend Herman (J.R. Cruz, another newcomer), a serious A-student who pushes for a bit of sex.

In what an obstetrician (Joanie Tomsky) later affirms a rare but not impossible phenomenon, which, without belaboring religious implications, the immigrants will view as a “miracle,” she becomes pregnant without actual penetration. Ernesto angered more by what he insists is stiff-necked lying, Magdalena, too, moves in with loving never-married Tomás. Herman makes a scared attempt at being supportive but semi-lies and caves in to the protective mother (Teresa Michelle-Ruíz) who sends him away to safety and continuation of his studies.

In the gentrifying neighborhood, word leaks out, so the world is reduced to the glass-hung garden and family photograph-filled home and its occupants, Tomás, Magdalena and the growingly sympathetic Carlos. But not entirely, because, rumored to be homosexual but not, the boy is casually drawn into a threesome with the two well-off whites who buy and move into the house at 1023 Water Street.

It does seem disingenuous of American Glatzer and British Westmoreland to have said it’s only coincidence that the story’s pseudo-worldly gays are American James (casting director Jason L. Wood) and six years younger British Gary (David W. Ross). In any case, both film characters are stereotype supercilious, surrounded by Anglo friends at parties yet manipulative and drawn particularly to Latinos. Even the younger Brit is still a dozen years Carlos’ senior, and both men show their true selfish colors when an eviction notice arrives at the downstairs unit where Tomás has lived for twenty-eight years, precipitating the crisis in which, with a hinted gesture from a kindly white lesbian, Magdalena and the more forceful Carlos will mature into adult responsibility.

A death brings sorrow and yet a sense of continuation, a new generation picking up the torch. Apologies tendered, forgiveness granted, reunions tearful, the family endures and happy tradition continues. With work and education in the offing, these, too, will move upward.

(Released by Sony Pictures Classics and rated "R" for language, some sexual content and drug use.)