The iconic film was released in April 2004 and also starred Judy Greer and Andy Serkis.

Mark Ruffalo has nothing but incredible things to say about his 13 Going on 30 co-star, Jennifer Garner, nearly 20 years after the film was first released.

Talking with ET’s Rachel Smith at the 2024 National Board Of Review Awards Gala in New York City on Thursday, the Poor Things actor, 56, explained what initially brought him to the project and why it was the “wonderful chemistry” he had with Garner, 51, that hooked him.

“It was my first kind of studio film and, you know, I’d been doing pretty small indies up to that point and Gary Winnick, our director, said ‘I want to — I want to do a small indie but in a rom-com studio film,’” he said, adding that the Winnick told him he would be opposite the Alias actress.

“It was Jen Garner, who is just magical, and we had just a wonderful chemistry together,” the Avengers star said.

The film released in April 2004 and became an instant classic, boosting Ruffalo and Garner’s own careers astronomically. Garner went on to star in Elektra, Juno, and Ghosts of Girlfriends Past while Ruffalo took on roles in Collateral, Zodiac and Shutter Island. He credits 13 Going on 30 with helping him to reach the next stage in his career and being cast in “elevated roles.”

“I think people started to see me in a lot more different kinds of elevated roles than what I’d been playing up to that time,” Ruffalo said.

As for what he would consider his favorite scene from the movie, Ruffalo said it’s the tender moment between his character and Garner’s on a swing set outside of New York City that comes to mind.

“Probably the Razzle scene on the, out on the swings in the park,” Ruffalo said. “Yeah, beautiful, sweet scene.”

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In 2022, while promoting their movie, The Adam Project, Garner shared a photo of her and Ruffalo recreating a scene from the romcom. “13 Going on 30 Reunion, aka #TheAdamProject, is out Friday on @netflix. ♥️,” she captioned the post.

In The Adam Project, the pair play a husband and wife, whose son, Adam, played by Ryan Reynolds, travels back in time to team up with his 12-year-old self (Walker Scobell) for a mission to save the future.

Talking with ET at the time, the actors both said the reunion was much needed for them.

“We did 13 Going on 30, went on and had lives, families, and kids and all kinds of other stuff, and came back and it’s like, ‘Wow. what a journey we’ve taken,’ and here we are,” Ruffalo said of acting alongside Garner again.

“It was so lovely,” Garner gushed. “It was really comforting to be together again, and I don’t think either of us realized how much we needed it and how great we feel.”