Greta Gerwig can be scattered. But she likes to say that the greater the chaos and uncertainty, the calmer she gets.

When I met her at her office in Chelsea, she was very calm. This, despite the whirlwind: She’s six months pregnant with her second child, another boy. She’s promoting her star turn in a Netflix black comedy with Adam Driver and Don Cheadle — an adaptation of Don DeLillo’s 1985 novel, “White Noise,” directed by her partner, Noah Baumbach. And she’s editing a movie due out in July that she directed — and she and Mr. Baumbach wrote — that has generated giddy excitement, along with intense curiosity about Ms. Gerwig’s approach: “Barbie,” a cotton-candy-pink extravaganza starring Margot Robbie and, as the living doll’s consort, Ken, a platinum Ryan Gosling.

“I’ve just got to finish ‘Barbie,’” said Ms. Gerwig, 39, who was wearing a plaid shirtdress, black leggings and some black ankle boots she got at Liberty’s in London, the city where “Barbie” was mostly filmed. “I’m bad at focusing on too many things at once. I don’t have that kind of bandwidth.”

She sheepishly confessed that she was so busy that she had used dry shampoo that morning instead of taking a shower. But it’s hard to believe that Ms. Gerwig is a bad multitasker, given how many things she is juggling, including, on the day after we talked in her Chelsea office, hosting a big family Thanksgiving dinner for 20 in her downtown Manhattan apartment.

She has collected so many hyphens in her résumé that even Barbra Streisand would be impressed: actor-writer-director-producer and multiple Oscar nominee for the critical darlings she wrote and directed, “Lady Bird” and “Little Women.”

I had heard Ms. Gerwig was a great eater, so, even though we were lunching dutifully on Sweetgreen salads, we started off talking about one of her culinary delights: doughnuts.

“I think, particularly on film sets, I become the child version of myself that wants just junk food,” she said. She read that Steven Spielberg had wooed a reluctant David Lynch to play a cameo as John Ford in “The Fabelmans” by acceding to his request for Cheetos on the set. “Then I felt like a kindred spirit with David Lynch, since we have the same addiction to the salty, cheesy goodness of Cheetos.”

Inside the Dreamhouse

Will Ferrell, who plays the Mattel C.E.O. in “Barbie,” has said the movie is a homage and a satire. But details are scarce about how Ms. Gerwig solves the sticky issue of Barbie. Feminists have had their issues over the decades, saying the doll offered a superficial, beauty-centric view of women — in 1992, a talking Barbie burbled, “Math class is tough!” Under pressure, Mattel added different shapes and races and professions to the line. “Barbie believes in the power of representation,” the doll’s Instagram account boasted.

“My mom was a feminist, and I think there was some resistance to all of it and eventually there was relenting,” Ms. Gerwig recalled, describing hand-me-down dolls. “I think I was totally compelled by hair that was 10 times bigger than your body.”

Her own childhood hair, she recalled, was thin, which made Barbie’s all the more an object of fascination. Ms. Gerwig said she wanted the movie “to be something that is both able to come from the adult part of your brain and also remember what it was like to be a little girl just looking at a beautiful Barbie.”

She said the main draw for her in taking on the project was Ms. Robbie, who is starring and producing. “She’s so fearless,” Ms. Gerwig said. “There’s something really infectious about that. For some reason, I thought, ‘Yes, I would love to write this and Noah would love to write it, too.’ I don’t think I really checked with him. At first he was like, ‘What? What are we going to do?’ He was not sure. Then we both got really excited and fell in love with the project.”

In London, Ms. Gerwig and Ms. Robbie kicked off filming with a “Barbie sleepover” with some of the other women and men working on the movie (alas, Mr. Gosling didn’t participate) — complete with games, goody bags and pink sleepover outfits.

“I really love building companies of actors almost like a theater troupe,” Ms. Gerwig said. “I wanted that kind of energy because it was a really big cast. It was like, well, let’s do something totally girly.”

The director also showed movies every Sunday at the Electric Cinema in Notting Hill for the cast and crew, hoping to provide some style or comedy inspiration for the shoot: “His Girl Friday” for the manic pacing and “The Red Shoes” for the saturation of color. Ms. Gerwig said the message was: “Don’t worry. People have made really wild movies before.”

Even Ms. Gerwig seemed startled by the pictures of Ms. Robbie and Mr. Gosling as Barbie and Ken on a beach in Los Angeles that broke the Internet in June. “I couldn’t believe Ryan and Margot were just out there in full neon,” she said. “It was like we were in this bubble, and all of a sudden they were doing it in public in front of everyone. Everything was so extreme and they were really going for it. Just 100 percent commitment.”

Ms. Robbie recalled that, in order not to “waste brain power” on her wardrobe, Ms. Gerwig wore the same boiler suit, in different colors, every day of the shoot. “We did pink on Wednesdays,” Ms. Gerwig said.

Laurie Metcalf, who played the mother in “Lady Bird,” said that, on that shoot, Ms. Gerwig told people to wear a name tag revealing a movie that everyone else loved but you just didn’t get. Ms. Gerwig’s was “Breakfast at Tiffany’s.”

It’s funny, I noted, since she played free-spirited young women not unlike Holly Golightly earlier in her career, ones whose brio masked their vulnerability as they tried to make it in New York.

“I just never liked it,” she said of the Audrey Hepburn classic. “It made me uncomfortable. There’s something at its core I just don’t like.”

The First Couple of Film

In her early career, Ms. Gerwig’s quirky, wobbly, lovable persona in “mumblecore” films, then later in “Greenberg,” “Frances Ha” and “Mistress America” — she wrote the latter two with Mr. Baumbach and he directed both — made her the indie “It girl,” a successor to Diane Keaton in “Annie Hall.”

“She was a wonderful combination of an actress who can embody the character naturally but at the same time keep half of her brain working as a writer inside of the scene,” said Mark Duplass, who made mumblecore movies with her. He recalled directing her in “Baghead” in 2008, as she was putting a suitor in the friend zone; she improvised and put tiny hair clips in the young man’s hair while she was letting him down, as a way of letting him know.

It’s a shock to see Ms. Gerwig in “White Noise,” looking almost unrecognizable as Babette Gladney, the permed, sweatsuited wife of a Hitler-studies professor at a small liberal arts college in the Midwest.

“It was strange for our 3-year-old, who was 2 at the time, because he would come to the set and look at her and he had a hard time processing it,” Mr. Baumbach said.

Ms. Gerwig was thinking Teri Garr and Dee Wallace, as well as women she had seen in her hometown, Sacramento, as a child. “I got a really early, quick picture of Babette in my mind, and I saw her hair and I saw her in a lavender sweater,” she said. “I saw acrylic nails that were mauve. I was born in ’83. I have sense memories of being in the grocery store and the color of certain women’s nails.”

She worked out the look with Ann Roth, the Oscar- and Tony-winning 91-year-old costume designer who worked on the movie. “She would call me sometimes and say, ‘Gret, do you think that Babette is the kind of woman who has only red underwear or does she have a few other colors?’ I said, ‘I think she only has red underwear.’ Ann said, ‘That’s exactly right, red.’”

She cast herself in the role. “When Noah said, ‘Who do you think should play Babette?’ I said, ‘Me.’”

Since the first time she was directed by Mr. Baumbach a dozen years ago, Ms. Gerwig has become an acclaimed director herself. Did she ever want to correct him on how he was directing a scene?

“No, I think I only did it once on the set,” she said. “He’s incredibly open to suggestion. The truth is, I think if I had wanted to sit there all day, every day, even when I wasn’t on the set, he’d be happy to ask what I thought of every shot. I think also, as a director, there’s a certain loneliness. Mike Nichols said directors need a buddy. So someone who has a thought or a point of view or is looking over your shoulder makes you feel less like you’re having an isolated existential crisis every day.”

Was it uncomfortable when the two had to go up against each other at the Oscars for Best Picture of 2019, he with “Marriage Story,” she with “Little Women”?

“It was so weird in the moment when we actually were there,” she said. “It’s very funny, but we did actually vote for ourselves. We were at our computers and I was like, ‘Just so you know, I’m going to vote for myself,’ and he said, ‘OK, I’m going to vote for myself, too.’”

Mr. Baumbach told me that the Oscar face-off was “easier” because they both lost. “We could celebrate that together.”

Having been in competitive situations with journalists I was dating, I was impressed with their equanimity, especially with Mr. Baumbach’s apparent lack of an overweening male ego. Ms. Gerwig has addressed this in her work; in “Mistress America,” Lola Kirke’s Barnard student is interested in a guy in her class, even as the two compete against each other to get into a prestigious writing club and she wins a spot. He gets involved with another young woman and dismisses Ms. Kirke’s character, saying: “I need someone I can love, not keep up with.”

“I feel like it must be hard if you’re 25,” Ms. Gerwig said. “I think as you get older, things work, things don’t work. You’re up, you’re down.”

I explained that my illusions about the glamour of being “the first couple of film” — as The Hollywood Reporter called Ms. Gerwig and Mr. Baumbach in 2019 — was shattered long ago when I interviewed Paul Newman and Joanne Woodward, that earlier first couple of film. Ms. Woodward said she would not participate in the 1986 New York Times Magazine cover story about Mr. Newman because she did not give quotes for stories that were focused on him, rather than on her or both of them. Mr. Newman appealed to her but was rebuffed. Later, I interviewed them both for the cover of a women’s magazine, and Ms. Woodward was charming.

Ms. Woodward had talked about “the tough fight” and many years of analysis involved in keeping her own identity, and I was left wondering: How many hours with a psychiatrist did it take to work those rules out? Clearly, even in this most enduring of Hollywood marriages, careful ego management was required.

Even though Ms. Gerwig seems more excited to take on big commercial projects and Mr. Baumbach seems more fixated on capital A Art, they make their collaboration seem suspiciously easy and fun. (Perhaps it has something to do with Ms. Gerwig’s high school obsession with the sport of fencing.)

She is hesitant to say this on the record because “it feels very cheesy to me,” but finally it tumbles out: “He’s my favorite person ever to talk to and I think I might be his favorite person to talk to.”

She recalled a time in the early pandemic when they were still in isolation. “I was in the kitchen and he hadn’t woken up yet. I had a thought and I thought to myself, ‘I can’t wait until Noah wakes up and then I can tell him this.’ I thought, ‘He’s the only person I see and I was still excited to talk to him.’”

Ms. Kirke said that Ms. Gerwig, who co-wrote and acted in “Mistress America,” and Mr. Baumbach, who co-wrote and directed, presented “a united front on set together. You can see how inspired by and respectful they are of one another.”

Ms. Kirke never saw them fight, she said, adding that she had been in situations with other husband-and-wife teams and thought they must “hate each other.”

A Working Romantic Partnership

Mr. Baumbach first worked with Ms. Gerwig on the 2010 movie “Greenberg,” starring Ben Stiller. Mr. Baumbach directed the movie, and wrote it with Jennifer Jason Leigh, then his wife, who also acted in it and served as a producer.

Clearly, some life-altering alchemy was at work between the 40-year-old Mr. Baumbach and the 26-year-old newcomer Ms. Gerwig, who played a personal assistant. (She trained for her role by working as a personal assistant for a month to Ms. Leigh’s mother, Barbara Turner, a screenwriter.)

I told Ms. Gerwig it’s easy to see now, rewatching their first movies together, that the director was infatuated with her. “I’m turning red,” she said, a blush spreading over her ivory skin. Mr. Baumbach midwifed Ms. Gerwig’s stardom; in the Times review of the film, A.O. Scott declared that she “may well be the definitive screen actress of her generation.”

Ms. Leigh filed for divorce eight months after the birth of her son with Mr. Baumbach, who was born just before “Greenberg” came out. The divorce was not finalized until 2013. This bitter, chaotic time informed Mr. Baumbach’s “Marriage Story.”

Was it difficult establishing a relationship with Ms. Gerwig amid the wreckage?

“I was going through a hard time in my life, and she was going through a different time in her life,” he said. “We really wanted to make it work together, we really wanted to be together, and we were both drawn by that. That’s how we still feel about each other.”

He said that he and Ms. Leigh — who has stayed publicly silent about the dissolution of the marriage and her opinion about “Marriage Story” (although Mr. Baumbach told The Wall Street Journal that he screened it for his ex-wife and she liked it) — co-parent their 12-year-old son, Rohmer. “In another completely different way,” he said, “you have to work together on that so that you can be the best parents you can to your great kid.”

His partnership with Ms. Gerwig — they are not married but she wears an engagement ring — has changed him, he said. “I feel like I’m a better artist because of it,” he said. “I know I am. I think a lot about ‘Marriage Story,’ which she didn’t write with me, but the things I was able to do with that movie as a direct influence of just being in a relationship with her and being around her, and things that she’s brought out in me that I was maybe sitting on.”

Like what?

“I think a joy of looseness,” he said. “I’m less afraid of being embarrassed.”

Mr. Baumbach said he’s not immune to competitive feelings, but dryly noted: “I’ve been in a ton of therapy.” He continued, “If I show her something I’m writing, or I show her a cut or something I’m working on that she’s not directly involved in, the highest compliment she pays is, she says, ‘I’m jealous.’” He mused, laughing and echoing Ms. Gerwig: “Maybe if I was 25 and met her, I wouldn’t have been able to handle it.”

In a way, the couple’s early collaboration replicated the dynamic between Woody Allen, Mr. Baumbach’s early idol, and Diane Keaton, an idol for Ms. Gerwig. Ms. Gerwig brought a kooky, boho California lightness to Mr. Baumbach’s darker coiled, neurotic Jewish New York sensibility.

In the beginning, did people think she was the Hollywood ingénue riding on Mr. Baumbach’s reputation? I remind her of the time Barbra Streisand asked Steven Spielberg to watch an early cut of “Yentl,” and then a lot of people falsely assumed he had directed it. Ms. Gerwig grinned and said she showed Mr. Spielberg an early cut of “Little Women” to get his notes, and no one assumed he had directed it.

Ms. Gerwig said that before she started directing, some people assumed that she was just contributing some extemporaneous lines to films she was starring in and Mr. Baumbach was directing, like “Frances Ha” and “Mistress America.”

“People would say things like, ‘Did you help to write the script?’” she recalled. “I was like ‘No, I co-wrote it.’ I think the more work I did and the more authorship I took on, the less that was something that was a question mark. People are more like, ‘Oh, she probably did write those with him because now we can see this work or that.’ That assumption of ‘Oh, you probably didn’t do this really,’ that’s gone away.”

Mr. Baumbach wryly said it goes the other way now, with people talking about “Frances Ha” as though it’s Ms. Gerwig’s sole creation.

‘Her Ambition Is to Conquer American Cinema’

Saoirse Ronan, a star of “Lady Bird” and “Little Women,” said that Ms. Gerwig, like the director Steve McQueen, was “a bundle of energy, ideas and inspiration. She was constantly rewriting scenes to make the script as tight as she could. She’ll work all the hours that God sends.”

Ms. Ronan said that in “Lady Bird,” a nun tells her character that the greatest form of love is to pay attention. “That came from Greta directly,” she said. “She pays absolutely incredibly sharp attention to everyone and everything around her.”

Amy Pascal, a producer of “Little Women,” was equally effusive. “She barged into my office and said, ‘You have to hire me to write “Little Women,” and I want to direct it, and here’s why. I want to tell the story in a completely different way.’” She told Ms. Pascal: “It’s about money.”

“She was able to decipher the book to tell it in a really modern way,” Ms. Pascal said. “Her ambition is to conquer American cinema.”

Ms. Metcalf said the key to Ms. Gerwig’s success as a director is dogged preparation. “She does all of the homework before anybody gets to the set,” she said, eschewing the usual mad scramble. “There’s a lightness there. She takes away all the pressure.” Instead of being the type of director who withholds praise from “the children” and whispers about the actors behind the monitor to make them paranoid, Ms. Metcalf said, Ms. Gerwig “keeps a bubble around you, so no negative feelings are allowed in.”

Before they began filming “Lady Bird,” Ms. Gerwig brought the cast over to her New York apartment and showed them a shoe box of mementos she had kept from high school, saying, “Here’s how I see the character.”

“That clicked with me in a way that was rare,” Ms. Metcalf said. “That made it so real to me. It was the first time I was playing a fictional character where I actually was able to think of it as a real woman.”

Ms. Gerwig and Mr. Baumbach both like to blend autobiographical elements into some of their movies. Does it ever feel like you’re sucking out each other’s emotional DNA, I asked her, or studying each other for good material?

“He’s working on something right now, and I’ve been reading it as he’s working on it and I said, ‘You know what?’ and I gave him this little story and a good line and then he put it in,” she said. “And then I read another draft and I was like, ‘Listen, if you’re not going to use that line, I’m going to use it.’ He said, ‘No, no, no, I’m going to use it. Don’t worry.’

“Some little things are flattering,” she continued. “There was something in ‘Marriage Story’ with the Scarlett Johansson character, Nicole,” who was widely understood to be a stand-in for Ms. Jason Leigh but shared some of Ms. Gerwig’s traits. “In the beginning, when Charlie and Nicole are talking about each other and he says, ‘She makes tea and leaves it all over the apartment and she leaves the cabinets open.’ And my friends watched it and were like, ‘That’s you. You do those things.’ I was like, ‘It’s true. It is me.’

Mr. Baumbach laughed when I asked him about it. “She pours herself water, then puts it down somewhere and then never drinks it,” he said. “There are usually five of them around.”

As sunset neared and New Yorkers scurried off to trains, planes and automobiles, getting ready for Thanksgiving, Ms. Gerwig cleared our plates from lunch and went to the fridge in the kitchen to make herself some yogurt with honey and cinnamon. Then she got back to work, cutting “Barbie.” After writing for so long about the paucity of women directors, I tell her as I leave, it’s great to see a woman behind the camera smashing it, and doing it like a woman, not a man.

“I hope to continue to do so,” she said, as she disappeared into an editing room. “I hope I make movies all the way through my 70s, maybe my 80s. We’ll see how I go.”

Confirm or Deny

Maureen Dowd: You threw up on a yacht in front of the Kardashians.

Greta Gerwig: It’s true. I had never been on a yacht and I was so excited to, and then five minutes after being on one, I threw up in front of two Kardashians. I haven’t been on a yacht since. I don’t think this is a big memory for them. Only for me.

Your greatest accomplishment was forcing hipsters to like the Dave Matthews Band after “Lady Bird.”

I don’t think I had to force anyone to do anything. I think they all secretly loved it just like I do, and they just had to admit it to themselves.

Your favorite sex scene is Donald Sutherland and Julie Christie in “Don’t Look Now.”

Yes, I stand by that.

You avoid sex scenes when you write your own movies.

I’m not interested in the sex scene just for the sex scene of it. It would have to be something where it felt part of the story. I might write one eventually.

You want to make a musical.

Musicals are always top of mind for me. I would love there to be a musical in my future.

You forbid cellphones on the set.

Yes.

Your favorite place to eat in Brooklyn is Court Street Grocers.

Yes. They actually have one now in Manhattan.

You make your own baby food.

(Laughing) Not anymore. It’s a lot of puréeing. I’ve forgotten all of this. I’m going to have to remember how to do all this stuff.

You grew up in a house without a television.

There was a little black-and-white set that they plugged in, they kept it in the closet. My parents were hippies a bit. They didn’t really want us to be inundated. We weren’t allowed to wear logos on our clothes. My mom felt that it was turning us into billboards.

You said your fallback career is tutoring “rich, stupid kids.”

No, my fallback career is being a step aerobics instructor, which I’m certified in.

You bring a posse of college friends to the Vanity Fair Oscar party and they all dress alike.

Those are my best friends. One’s a nurse, one’s a social worker, one’s a lawyer, one’s an actor. It was their idea because I was like, “I don’t know if I can get everybody into the Vanity Fair party.” And they said, “If we all wear the same outfit, they’ll think we’re part of something and then we’ll be able to find each other easily.” They wore a print from a designer in Brooklyn the first time and five different yellow dresses the next time. It’s going to get weird as we get older.