People have been trying to figure out twentysomethings at least since Dustin Hoffman unzipped Anne Bancroft's dress. In 2010, The New York Times Magazine ran a late-to-the-game article about a "new" life stage called "emerging adulthood" (a phrase coined by a psychology researcher a decade before) when self-indulgence and self-discovery collide.

The exuberant and disarming Frances Ha is a portrait of one such emerging adult, shot in resplendent black-and-white and scored like a French New Wave film. As played with haphazard elegance by Greta Gerwig, Frances is a 27-year-old aspiring dancer in New York City still lurching through the obstacle course of a privileged post-collegiate life. Sometimes life is a playground, as when Frances and best friend Sophie (a snappy Mickey Sumner) play fight in Central Park or snuggle platonically in their apartment. And sometimes it's a minefield, with the perils of adulthood blowing up without warning in Frances' face, as when Sophie announces she's moving out. The transformation of this friendship—Frances compares them to "an old lesbian couple that doesn't have sex anymore"—sends our protagonist skidding. While Sophie grows more serious about her hedge-fund boyfriend, Frances remains needy, frequently oblivious of others and prone to hogging conversations with directionless soliloquies. Yet she's immensely likable. Gerwig strips her performance of affect or cutesiness; unlike those manic pixie dream girls, she's not being quirky just to snag a guy.

In fact, aside from a throwaway boyfriend in an early scene, Frances is single throughout. A male roommate pronounces her "undatable," which she reinforces by emitting a robotic honk when trust-fund playboy Lev (Girls' Adam Driver) makes a move. This non-romantic bent lends Frances Ha freshness, amplified by the rhythmic, sprightly screenplay, co-written by Gerwig and Noah Baumbach. "I'm not messy, I'm busy," says Frances. Later, after a squabble, she sputters at Sophie: "Don't treat me like a three-hour brunch friend!" It's fluid yet fizzy, specific yet eminently relatable.

In one of the loveliest moments, David Bowie's "Modern Love" plays as Frances spins through the streets. Backpack bouncing, floral-print dress cutting a contrast with the crosswalk striping, she's every bit the emerging adult: aimless yet hopeful, self-absorbed yet in wide-eyed awe at the big, beautiful world. And as the audience, we're lucky to run alongside her.

Critic's Grade: A-

SEE IT: Frances Ha is rated R. It opens Friday at Cinema 21.