Greta Gerwig, best known for her “Mumblecore” roles, says the awkwardness associated with her characters is “certainly not something I try to cultivate.” (Myles Aronowitz/MYLES ARONOWITZ)

In “Lola Versus,” which opened Friday, Greta Gerwig (last seen in “Damsels in Distress”) plays a woman whose life goes awry shortly after she turns 29. Gerwig, who will turn 29 this summer, says she has seen enough friends undergo turmoil at around the same point to believe that approaching the Big Three-Oh really does trigger existential crises.

“I feel I’ve already lived through turning 30 on film, so maybe it’ll be easier,” she says laughing. But “everything approaching 30 is just sort of fraught” with questions about how the signifiers of adulthood — home ownership, marriage perhaps, maybe children — are going to materialize. She confesses, with some embarrassment, that her own list of pre-30 goals is somewhat ambitious: “Win my Oscar for best screenplay. Win the Pulitzer.” Laughing, she says, “I just want prizes.”

She’s eager to explain this isn’t about vanity but the desire to have done good work, and that “prizes are a pretty good external marker. I feel I’m always trying to make myself into a person who does not care about external validation, but the truth is I do, and I think most people do. I think it’s exhausting to try to pretend you don’t.”

A screenwriting Oscar is a big goal for someone whose only credits so far are for co-writing films that were largely improvised by their casts. Gerwig arrived on the indie scene in 2007 with “Hannah Takes the Stairs,” one of a few movies she has made that are lumped with similar no-budget, dialogue-heavy films under the label “Mumblecore.” Though those movies led to roles in Noah Baumbach’s “Greenberg” and the Hollywood comedy “No Strings Attached,” Gerwig has often expressed shock, even horror, that audiences ever saw them.

She describes the short period of making those films as one of on-the-job learning, hashing things out on-screen in a way that doesn’t appeal to her now. These days, she wants to know what she’s doing before the cameras roll.

“I think improv is very helpful for finding what’s interesting about a scene, or deepening the acting choices or relationships, loosening people up, getting new material,” she says. “But then I’m interested in taking that and honing it. I don’t think the raw material is as interesting as I once did; those moments are usually better when they’re crafted, Mike Leigh-style. I like to see crafted things when I go to the movies.”

Although on-camera improvisation works well in Judd Apatow-style comedies, she says, “those films, to me, end up feeling more like collages. I like films that feel more like poems,” with each element deliberately chosen. “I just like that authorship feeling.”

Her belief in authorship has roots. She studied literature in college and claims laughingly to be “thoroughly stuck in 19th-century literature. Every time I read a modern novel that has, like, bad words and pop-culture references, I feel a little bit affronted.” That sensibility made her perfectly suited to join bookish filmmaker Whit Stillman for “Damsels in Distress,” but threw her when she worked with Woody Allen (in the upcoming “To Rome With Love”) and learned how little he valued the words in his script.

“He comes up to you,” she explains, “and says, ‘I don’t know why you’re saying it like this.’ And you say, ‘Uh, well, that’s the line.’ And he says, ‘That’s a terrible line! Make up a new one.’ ”

Gerwig says she was too terrified to analyze Allen’s technique (“I was scared I was going to get fired the whole time. My ability to analyze what happened was dampened by fear.”), but thinks that he knows exactly what he wants in terms of the script’s jokes, then relies on actors to give the surrounding dialogue a truthful sound.

Fans may find it easy to imagine Gerwig on Allen’s set, tangled in fear and self-consciousness. Admirers respond to a quality in her performances most often described as vulnerability or awkwardness. Gerwig is bewildered by that perception.

“Am I really that awkward?” she asks. “I’m not like a person who walks into a party and conversation dies off.

“It’s certainly not something I try to cultivate,” she continues. “In Whit Stillman’s movie, I didn’t feel I was being awkward at all. I thought I was being, I don’t know, very elegant.” She laughs. “But maybe that’s just part of it. Maybe I looked like an awkward person trying to be elegant.”

She will admit to a high degree of self-monitoring, to having “a lot of internal voices.” Acting silences them, she has realized, but they’re back in force when she does interviews: “I can hear myself say the wrong thing sometimes: lose the train of thought, not be able to find the right word or articulate something. I think I’m going to sound stupid. Someone is going to say I’m dumb or ditzy or some other horrible thing that I fight against” — and she’ll come off as the opposite of the impossibly high-functioning, ever-composed movie stars depicted in fluffy magazine profiles.

She knows she shouldn’t believe those articles, especially having been on the other end of them, but she can’t help herself. The subjects “just seem so cool and awesome, and I totally buy into it, every time.”

Which might be a good spot to mention how glamorous and composed Gerwig is for her own interview — dressed in a fashion-forward, zippered ensemble she describes as a tuxedo tracksuit, answering questions with charm and aplomb. The Oscar/Pulitzer double whammy may be a few years down the road. But if Greta Gerwig has “Become an actual movie star” on her before-30 to-do list, she might just manage it.

DeFore is a freelance writer.