All About Joaquin Phoenix and Rooney Mara's Son River

Joaquin Phoenix and Rooney Mara welcomed their son, River, in 2020

Joaquin Phoenix and Rooney Mara might be two of the biggest names in Hollywood, but the couple leads a very private life when it comes to their son, River.

Since they began dating in 2016, Phoenix and Mara have primarily kept their relationship under wraps — save for a handful of red carpet appearances and rare interviews. The couple first met in 2012 on the set of the sci-fi drama Her, but Phoenix thought Mara despised him.

Four years later, they costarred in 2016's Mary Magdalene and started dating. They made their red carpet debut as a couple at the Cannes Film Festival in 2017, and later that year, Phoenix revealed he and Mara were living together.

The pair privately got engaged in 2019 before welcoming their first child together in 2020. River was named after Phoenix's brother who died in 1993.

Mara always envisioned becoming a mother, having grown up with three siblings. "I love it. I love it so much," she said on her LaunchLeft podcast about motherhood. "I think it's the best thing in the world."

River will have at least one sibling, as Mara and Phoenix are currently expecting baby No. 2.

Here's everything to know about Joaquin Phoenix and Rooney Mara's son, River.

He was born in 2020

Phoenix and Mara's first child, a son named River, was born in 2020. The baby news was revealed by Victor Kossakovsky, a Russian filmmaker who previously worked with Phoenix on the documentary Gunda, at the Zurich Film Festival.

"He just got a baby, by the way," Kossakovsky said in September 2020. "A beautiful son called River."

Neither Phoenix nor Mara publicly acknowledged the pregnancy: The couple made rare red carpet appearances earlier that year — at the Golden Globes in January 2020 and the Oscars a month later — with no mention of a child.

The pair did, however, look more in love than ever, with Phoenix smiling admiringly as Mara posed on the Golden Globes red carpet.

He is named after Phoenix's late brother

Their son's name honors Phoenix's older brother River, who died on Oct. 31, 1993. River, who starred in films including Stand By Me, Running on Empty and My Own Private Idaho, was 23 when he died from a drug overdose.

Phoenix has spoken about his brother's lasting impact on his life, specifically as it pertains to acting. In September 2019, a year before his son's birth, Phoenix paid an emotional tribute to his late sibling while accepting the TIFF Tribute Actor Award at the Toronto International Film Festival.

"When I was 15 or 16, my brother River came home from work and he had a VHS copy of a movie called Raging Bull and he sat me down and made me watch it," he said, per Variety. "And the next day he woke me up and he made me watch it again. And he said, 'You're going to start acting again, this is what you're going to do.' "

Phoenix continued, "He didn't ask me, he told me. And I am indebted to him for that because acting has given me such an incredible life."

He referenced his brother again at the 2020 Academy Awards while accepting the award for Best Actor for his role in Joker.

"When he was 17, my brother wrote this lyric," Phoenix said about River, who was a singer-songwriter. "He said, 'Run to the rescue with love and peace will follow.' "

His birth fueled Phoenix and Mara's advocacy

In November 2020 — five weeks after River's birth was confirmed — Phoenix and Mara opened up in an exclusive op-ed for PEOPLE about the hundreds of migrant children who were separated from their parents at the U.S.-Mexico border by immigration officials. It marked the first time the actors and activists had spoken publicly about their son.

"As new parents, it's unbearable to imagine what it would feel like to have our child taken away from us for a day, let alone years," the couple wrote. "But that's the very situation those 545 children and their parents have been living through."

They felt it important as Americans to continue the dialogue about "the policy of family separation." Phoenix and Mara also touched on what a conversation with River would be like about the situation.

"How will it feel to explain to our son, when he asks us about this time and how we treated scared, defenseless children, some of whom may never see their parents again?"

They concluded, "For the sake of our nation's character, I hope we will be able to tell him that America unequivocally rejected this cruelty and demanded that our representatives did everything in their power to find those missing parents."

He opened up his mom's heart to a "new life"

While celebrating her first Mother's Day in May 2021, Mara revealed that becoming a mother to River had "opened her heart." The candid admission about how parenthood had changed the actress came in a heartfelt letter written for Farm Sanctuary's Mother's Day campaign, which was shared with PEOPLE.

"As a new mom, Mother's Day has taken on a special meaning this year. Raising our baby, River, has opened my heart to a whole new life filled with hope and more determination than ever to create a kinder and more sustainable world," the actress wrote.

In the letter, Mara also spoke about mothers in the animal world. She highlighted three "extraordinary" animals — Henrietta turkey, Jackie cow and Cynthia goat — who survived dire circumstances and beat the odds while still sharing their affection with others.

"I feel so fortunate to be able to nurture my son in all of the ways that nature intended and I wish all mothers in the animal kingdom could experience that sacred maternal bond with their young, devoid of exploitation by humans," she continued.

The letter concluded, "As I celebrate my first Mother's Day, I hope you will join me in honoring all of the inspiring moms and maternal figures who've made a difference in your life. With love, Rooney Mara."

Phoenix hopes his son will be a vegan

Phoenix, who has been a longtime vegan, hopes his son will follow a similar path — but won't force him. In a 2021 interview with the U.K. newspaper The Times, the Oscar winner revealed that he would let River make informed lifestyle choices.

"Well, certainly I would hope that [he is vegan], but I'm not going to impose my belief on my child. I don't think that's right," Phoenix said.

Instead, the actor — who is vocal about animal rights and climate change — plans to educate River from a young age on the realities of the food system.

"I'm not going to tell him that it's okay to read books about all the wonderful little farm animals ... and not tell him that that's what a hamburger is," he continued.

Phoenix added, "So I'm not going to perpetuate the lie, but I'm also not going to force him to be vegan. I'll support him. That's my plan."

He has spent time on set with Mara

Mara's first acting role after giving birth to River was in Sarah Polley's 2022 film Women Talking. The Nightmare Alley star spoke about her experience as a working mom with Phoenix's sister Rain on LaunchLeft in January 2023.

"This was sort of my first job that I had done as a mother, and so it was a really important experience for me because I wasn't really sure if I could work, if I can do both," Mara shared. "I still don't know, but Sarah [Polley] made it possible on this, that we were working 10-hour days."

Mara balanced her acting work with parenting a toddler by frequently bringing River to set with her. She also turned to her fellow costars for motherhood wisdom.

"I was able to get advice from Claire [Foy] and Sheila [McCarthy] and Judith [Ivey] and all these moms that I was working with, and River was there on set all the time, in the green room," she said. "It was a very idyllic situation, it probably won't happen like that again."

Though Mara doesn't expect to replicate the working environment of Women Talking, she does plan to continue to be selective in the roles she takes on — allowing her to spend as much time with River as possible.

"I'm so lucky that I have the choice to get to be with him most of the time," she continued. "I'm like, 'Oh, I'm just going to work once a year if something feels right and other than that, this is what I'm doing.' Most people don't have that option."

Phoenix and Mara are raising him in a "creative household"

Though Phoenix and Mara both work in Hollywood, she revealed their home doesn't revolve around movies because of their schedules.

"It doesn't feel like a two-actor house because I didn't work for the first three and a half years we were together," Mara said on LaunchLeft. "Basically, since we've been together, I only worked one or two times and one was really small and short."

However, that doesn't mean they don't expose River to their craft.

"It feels like a creative household, we're constantly talking about creative things," she added.

He is going to be a big brother

Phoenix and Mara are currently expecting their second child. The Women Talking star revealed her pregnancy on the red carpet at the Berlin Film Festival in February 2024.

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