Marching to a drum just off-beat enough, Diabolo Cody earned  herself an original screenplay Oscar with Juno and won over public and talk-show hosts alike. Unlike that other recent teen pregnancy comedy, Quinceañera, hers ignores any social and legal ramifications and pretty much stakes its all on a low-profile cast that grows considerably stronger after off-putting opening sequences.

In teenspeak, that introductory material is commented on by Juno MacGuff (Ellen Page): a short experimental sexual union with tic tacs chewing friend/boyfriend Paulie Bleeker (Michael Cera), followed by four DIY pregnancy tests bought from an unsurprised wisecracking convenience store clerk. Undeniably in the family way, the sixteen-year-old turns over alternatives with cheerleader best friend Leah (Olivia Thirlby) and, in her own unique way, announces her condition to Paulie as he heads for school track team practice.

Like most off-screen voices, the cucumber-cool heroine’s does not know when to stop, either, and so goes on to exposition about junior-year classmates and classes and, at length, her family, some of it totally beside the point and all of it subsequently acted out, anyway. Although wishing that the problem were DUI, hard drugs or expulsion from school, working class father (J.K. Simmons) and stepmother Brenda (Allison Janney) take the news in good stride and are unquestioningly supportive, he quietly and “Bren” even coming to defend her heatedly and vocally to a prenatal-care technician.

Turned off by the Women Now abortion counselling service for “nipping it in the bud,” with Leah’s help Juno glances over adoption-wanted ads in Vancouver’s Penny Saver and picks out the Lorings from their included photo. Love in his “my irresponsible child,” Dad accompanies “Junebug” to upscale Glacial Valley Estates, where, already disappointed once in seeking a child, the couple offer monetary compensation and are indeed attractive, she (Vanessa, played by Jennifer Garner) a professional woman and he (Jason Bateman, as Mark) a frustrated rock musician successfully composing consumer jingles at home.

Juno’s innocent openness delights the childless Lorings, and legal papers for an old-fashioned closed adoption are scarcely necessary. The teenager misunderstands “trimester,” as in three months of pregnancy, and the film itself is partitioned into printed trimesters of the seasons, from Autumn and, after the blessed event, finishing up with a brief Summer of kindness, of adoptive motherhood, and love rooted in friendship.

In Winter the expectant girl makes unwise return visits to the Lorings’ house, to report on “how your kid’s cooking” but also to share a taste for rock music and gory horror flicks. As she does, cracks appear in the ideal couple’s façade, chinks that the viewer will have sensed before her and that are hinted at in, for instance, Mark’s “Do we come across as paranoid yuppies?”

This ninety-two-minute small movie becomes larger as it develops, certainly as the characters reveal depths unsuspected at first glance.

Jason Reitman’s direction is no more than straightforward. Juno did not win in its two other Academy Award categories, is on some counts unrealistic, and does not probe deeply, but it has undeniable charm. Before, Juno did “not really known what kind of girl I am.” She remains a girl, but an older and a wiser one, kind and understanding more about herself and others. 

(Released by Fox Searchlight and rated “PG-13” for mature thematic material, sexual content and language.)