Jesse Eisenberg is known for playing Mark Zuckerberg in “The Social Network,” but that pivotal role didn’t stir up fascination of social media for the actor-turned-director — in fact, Eisenberg is not a fan of social media, whatsoever.

But in “When You Finish Saving the World,” Eisenberg explores the relationship between social media and social justice, as Julianne Moore and Finn Wolfhard play a mother and son who can’t seem to connect. Moore portrays a woman who works at a domestic violence shelter, and Wolfhard co-stars as a young social media star.

“When You Finish Saving the World” marks Eisenberg’s feature directorial debut, and is based on the Audible book he created in 2020. Eisenberg also serves as the screenwriter on the A24 project, which debuted at Sundance earlier this year and is now playing at the Cannes Film Festival.

“I got the script that Jesse had written, and I’m always really attracted to great writing,” Moore said at the Variety Studio presented by Campari at the Cannes Film Festival. “And it was so wonderful on the page and so unusual and the character was so complicated. I was drawn to that right away.”

Moore calls Eisenberg an “incredible director” and says Wolfhard was like a “peer” on set. “It’s interesting to work with a teenager who actually just brings it like an adult,” she says.

“She’s the greatest in the world,” Eisenberg says of casting Moore in the lead role. “I mean, that’s an objective statement of fact — not my, you know, unique fetish.”

Wolfard, known for Netflix’s “Stranger Things,” has more than 20 million Instagram followers in real life. Eisenberg, meanwhile, says he has an “ambivalence” to social media. “To me, it just feels so overwhelming, but he navigates it,” Eisenberg says of Wolfhard. “And that, to me, is the difference in the generation.” Eisenberg adds that “being in the public eye and not wanting anybody to know anything about my personal life,” he feels “compelled just by virtue of it being the air that we all breathe to be on these things, where you divulge information about yourself.”

Moore has a notable social media presence and uses her platforms to speak up about social issues, including gun control. Most recently, she signed an open letter supporting female reproductive rights. (“Fundamentally, I believe in a woman’s right to choose,” she says.)

As for her relationship to social media, Moore relates to the film’s subject matter because balancing social media with the important things in life is “the conundrum that we feel like we’re in all the time,” she explains. As an actor, she says, “We are as serious as we can be about the work that we do, and we take it very, very seriously. [But] we obviously are making entertainment. You hope that you’re making stories that make people reflect on who we are and how we live, and we need that as human beings. However, in the big scheme of things, you sometimes feel — I do, as an actor, anyway — somewhat on the margins of what is important. Like, ‘Is this a necessity?’ I don’t know. And yet, I feel compelled to do it. So that dichotomy, that push-pull is kind of evident in the film, right? And I think it’s something that I feel every single day.”