It's autumn. We know that because the animated letters in the upper-right corner of the screen say so. Juno MacGuff is standing on the lawn guzzling Sunny D and staring at a recliner. It won't be long until we find out why.

Juno (Ellen Page) is pregnant. The high school junior confirms this after a stroll through a set of animated titles to the local pharmacy, where she's greeted with the words, "Well, if it isn't MacGuff the Crime Dog. Back for another test? Third test today, Mama Bear. Your eggo is preggo. No doubt about it."

It's a scene that pretty well sets the tone for the 93 minutes to follow. Juno is that rarest of films: a quirky comedy about a very serious subject, chock full of irreverent dialogue but not at the expense of very real feelings and very believable characters.

At the center of the action, of course, is Juno, a guitar-strumming, flannel-clad neo-punk living in modern-day Minnesota. Like many girls her age, she's surrounded by a dysfunctional family at home and a dysfunctional lab group in school.

The only thing in her life that seems to work is her friendship with Paulie Bleeker (Michael Cera of Superbad and Arrested Development fame), and that now appears to be on the endangered list, a result of their unprotected tryst in a recliner not unlike the one Juno was staring at in the opening sequence.

Her first impulse is to get an abortion, but she quickly changes her mind after a classmate (Valerie Tian) who's protesting at the local abortion clinic informs her that fetuses have fingernails. On to plan B.

Plan B is to find adoptive parents for the baby. Juno -- possibly the deepest, most thought-provoking teenager to appear on an American movie screen in the last generation -- wants to be sure the baby will be raised in a loving, nurturing home. Fortunately, her friend Lea (Olivia Thirlby) directs her to "Desperately Seeking Spawn" ads in the local Pennysaver, and who should turn up but Mark and Vanessa Loring (Jason Bateman and Jennifer Garner), a pair of St. Cloud yuppies who are on at least their second adoption attempt.

Problem solved? Hardly. As in all good films, the new characters simply bring with them a whole new set of baggage: in this case, two sets. The ever-anxious Vanessa seems overbearing in the extreme, while the laid-back Mark -- a former punk rocker who now writes music for commercials -- seems a little too laissez faire, not to mention drawn to the very attractive Juno.

Then there's the little matter of Juno's relationship with Paulie; neither seems quite sure what he or she wants, though Paulie seems a little less unsure than Juno.

And then what about all those schoolmates of hers? In one of the film's best visual moments, Juno waddles up the hall in one direction as her classmates pass by her, all coming the other way and parting like the Red Sea at the sight of her. It's not too hard to guess what's on their minds.

Neither can we forget Juno's family, especially her dog-obsessed, nail-technician stepmom Bren (Allison Janney) and her dad (J.K. Simmons), a former military man who now does HVAC repair. (Juno's birth mother long ago ran off to an Indian reservation, we're told, and now sends Juno a cactus every year on Valentine's Day.)

Then there's the little matter of class warfare, probably best realized in the scene where Juno and her dad drive their well-worn van to the Lorings' to discuss the terms of the adoption. After passing a multitude of McMansions, they arrive at the Lorings', where they sit down in a living room the size of the MacGuff's house.

"Did you ever feel like you were just born to do something?" Vanessa Loring asks them as they discuss the Lorings' reason for wanting to adopt Juno's baby. "Yes," replies Mac MacGuff. "Heating and air conditioning."

So there you have it -- a witty and insightful script by former stripper and phone-sex operator Diablo Cody, brought to the screen in delicately nuanced form by director Jason Reitman (Thank You for Smoking) and performed by a cast of incredibly talented actors, including three under the age of 20.

Juno won an Academy Award for best screenplay written directly for the screen and was nominated for Oscars for best picture, directing and performance by an actress in a leading role. More importantly, it's a work of art. Really fun art. And touching, too.