“Frances Ha” is now playing at Sundance Cinemas. R, 1:26, four stars out of four.

“How much longer?” Frances’ mother shouts through the locked bathroom door as Frances (Greta Gerwig) floats in the bathtub, unwilling or unable to move.

It’s a question that Frances asks herself, over and over, in Noah Baumbach’s beautifully funny ode to twentysomething uncertainty, a universe of unmade beds and house parties, casual hookups and platonic roommates. In addition to giving a sparkling and deeply-realized performance as Frances, Gerwig also co-wrote the film with Baumbach (the two are now partners in real life as well). The result is a film that bears all of the zingy dialogue and sharp characterizations of Baumbach’s other films (“The Squid and the Whale,” “Greenberg”) but with more of a generosity of spirit towards its characters.

It’s also one of the most insightful movies about female friendship to come along in quite a while. The movie opens with a glorious black-and-white montage of Frances and her roommate Sophie (Mickey Sumner). The pair are inseparable (“We’re like the same person but with different hair,” Greta tells people), and we see shots of the pair scampering through the streets, having philosophical talks on fire escapes, cackling at house parties. It’s like the dream every Midwestern liberal arts student has about what life in Brooklyn would be like after graduation.

But every dream ends, and in New York, real estate is usually the culprit. Sophie gets the chance to live in Tribeca, and takes it. The two vow to stay close, but a gulf slowly widens between them that can’t be spanned by the Williamsburg Bridge. Sophie, in publishing, starts growing up, getting serious with her boyfriend, making new friends.

Frances, meanwhile, is caught in stasis. Her career as a professional dancer has stalled out, and she starts bouncing from apartment to apartment, humiliation to humiliation, watching as Sophie and others slide forward on their moving walkways to adulthood while hers remains closed for repairs.

It’s a familiar arc for Baumbach, heaping self-inflicted punishment upon punishment upon his characters, as we see Frances blather at dinner parties, her self-deprecating monologues becoming less and less entertaining to her audiences. But there’s a lighter touch here, and a poignancy, especially watching Frances and Sophie drift farther away from each other. There’s a deceptively cheery phone conversation late in the film, where Frances is just piling lie on top of lie about how well she’s doing, that’s just so sad compared to how honest and inseparable they had been.

She takes an ill-advised trip overseas which has to be the worst cinematic trip to Paris every committed to film. Conversely, when she goes home to Sacramento for the holidays, we brace ourselves for condescending comedy about life in the suburbs. Instead, it’s a lovely montage of images as Frances reconnects with her loving parents and old friends; her look of longing as she rides up the escalator to her plane back to New York is piercing.

Gerwig is a tremendously acute physical and verbal comedic actress, capturing the mix of grace and clumsiness with which Frances navigates every aspect of her life; we can see her do a beautiful pirouette in the dance studio, then get her ring stuck on her thumb on the subway ride home. She’s an equally lovable and maddening character, and we root for her to clean up the messes she can’t help make.

And it’s that rare film in which the heroine’s happiness or fulfillment doesn’t depend on her finding the right guy or not. A couple of guys move in and out of her life, but they’re largely in the background, and when she seems to finally find the right one, it’s nice, but not a make-or-break thing. She’s already found a place of her own.