Ellen Page as Juno MacGuff
Michael Cera as Paulie Bleeker
Jennifer Garner as Vanessa Loring
Jason Bateman as Mark Loring
Olivia Thirlby as Leah
J.K. Simmons as Mac MacGuff
Allison Janney as Bren MacGuff
Rainn Wilson as Rollo

Ever since James Dean screamed that he was being torn apart, the teenage coming-of-age drama has become one of the most overdone and underdeveloped of modern Hollywood films, transposed onto every genre from humor to horror, and usually all equally ill-conceived, until it seems as if all anyone who makes films knows about teenagers is what they’ve seen on screen.

When the teenage film does work, however, it can be a delight of drama and comedy, mixing just the right balance of precociousness and naivety, and Jason Reitman’s (“Thank You for Smoking”) “Juno” is a fine example of the form.

Ellen Page’s Juno is a smart ass, self-aware misfit, which sounds like she could have been plunked out of any half-baked John Hughes film, but in Reitman and Page’s hands is in fact a fully developed, fully engaged young woman, who is just aware enough to know that there is a great deal to life she is not fully prepared for. Unfortunately, she doesn’t fully come to this conclusion until after she’s gotten pregnant with friend Bleeker (Michael Cera).

The plot itself is generally inconsequential to the story, though. “Juno” is a character drama (and comedy) through and through. Her pregnancy is just an excuse to bring Juno into the orbit of young, seemingly upwardly mobile Vanessa and Mark (Jennifer Garner and Jason Bateman), who have been trying to adopt for some time. The world, for 90 minutes anyway, thoroughly revolves around Juno, through not just her interactions with the people in her world, but the way she watches them connect with each other. Like everyone, she’s the central character in her own story, but simultaneously an observer of everyone else’s.

It’s the little things that make life worth living, and the same is true for making a character film worth watching. The little things shine in “Juno,” from Rainn Wilson’s brief appearance as an acerbic drug store clerk, to the lone protestor of a small abortion clinic. Juno’s world bears little resemblance to everyday life – no one is ever at a loss for words, even when they’re at a loss for words – but there is no question that it’s real.

It takes a strong cast to make this sort of thing work, and Reitman has put together a fine one for “Juno.” In fact, there’s not a single wrong note in any of the performances, from Garner’s quiet desperation to J.K. Simmons’ surly but undisputed love for his daughter. Every part is perfectly cast, and everyone gets at least one moment to shine that exquisitely encapsulates who they are. The only downside is that with a relatively short running time and a decently sized ensemble, it feels like not everyone gets enough screen time. These characters are so well realized we’re usually left wanting more, and while that is undeniably a good thing, it’s also a little unsatisfying.

The real star, though, is blogger turned screenwriter Diablo Cody (AKA Brook Busey-Hunt), whose sharply observed script skirts the edges of indie film cliché, but never quite embraces them, deftly moving its characters through their paces instead, and always choosing genuine human interaction over easy melodrama.

All posturing aside, indie character drama has about the same success rate as Hollywood spectacle and for the same reason (usually reliance on well worked over stereotypes and cliché) but, like life, it’s the good stuff that comes along that makes all the dreck worth sitting through. “Juno” is the good stuff.