'Booksmart' Stars Beanie Feldstein and Kaitlyn Dever on the Secret to Their 'Special' Chemistry (Set Visit)

Booksmart Beanie Feldstein Kaitlyn Dever
Courtesy of Annapurna Pictures

"Authentic" and "refreshing" are two words the cast of Booksmart repeatedly use to describe the R-rated comedy, about best friends Molly and Amy (played by Beanie Feldstein and Kaitlyn Dever) who worked tirelessly all throughout high school to get the best grades and get into the best colleges, only to realize that they missed out on having any fun.

ET visited the set of Olivia Wilde's feature directorial debut in Santa Clarita, California, in June, where Feldstein and Dever, as well as co-star Billie Lourd, sat down with reporters to discuss their unforgettable time on set and why Booksmart is unlike any buddy comedy you've seen.

"The idea of two young girls in high school doing this comedy, where the comedy comes from their brilliance and their intense intellect, is so exciting," Feldstein, 25, tells reporters during a break from filming a classroom scene with the rest of the movie's young cast. "There are so many of these films that are so funny, but they're also silly. These girls, they're not that silly. They're so smart. It's exciting to see that duo at the center of this teen comedy."

Feldstein's Molly is unapologetic. She's not only senior-class president, but she's also valedictorian and is not to be messed with. Amy, meanwhile, is quiet, caring and, as Dever puts it, "I am more of good cop and she is more of the bad cop."

"They're like sisters. They really would do anything for each other," Dever, 22, relays. "It was just so refreshing and unlike anything that I have ever read before. And the fact that Olivia was directing, the whole package was so exciting for me."

For Feldstein, it was an opportunity to play someone she'd never played before.

"[Playing] someone that is a young woman who was unapologetically fierce in that way and very gun-ho and forward thinking was really cool," she explains. "And their friendship is so perfect, so special and loving. These are two girls who are so similar in so many ways but so different in other ways, but really, really love each other to the core."

That love transcends the screen and is clearly visible as the two sit next to each other. They finish each other's sentences, giggle while reminiscing about certain scenes and appear very much like real-life best friends. They credit their powerful chemistry to being roommates throughout the film.

"We actually got close off set, because we live together. We've been living together throughout the whole shoot, which has been so immeasurably important and special for us," Feldstein reveals, with Dever chiming in, "It has made a huge difference. Our chemistry would have been completely different if it hadn't been for spending 24/7 with each other."

"It has been so special in so many ways," Feldstein says. "We run lines every night. We eat pancakes in the morning. It's really neat. It's a once-in-a-lifetime experience."

Booksmart also proved to be a once-in-a-lifetime experience for Lourd, 26. The former Scream Queens star was immediately drawn to the project. "It is so damn funny and so authentic and real. That is what I love about it," she describes. "I actually created a word for it, hilareal, which is hilarious and real put together. You heard it here first."

Lourd plays Gigi. "No last name, because she speaks for herself," Lourd deadpans during a separate sitdown. Gigi is everything you love to hate, but absolutely can't get enough of. Her character is key in moving Amy and Molly's story forward, and while Gigi may be the life of the party, she also has her own personal battles.

"No spoilers, right?" Lourd giggles before revealing one. "Gigi really wants to be friends with Molly and Amy, but she lives in such a different world and she thinks that she’s going to become friends with them by drugging them with acid. But they don’t like friends like that. Like, she should stay in her lane, probably?"

"She is an aura-reading wizard of a being that shows up when you least expect her to and is just super over-the-top, really rich, the center of attention -- but deeply kind in her soul," Lourd adds. When asked what her late mother, Carrie Fisher, would think of Gigi and whether she felt her presence on set, she smiles, "[She's] always with me, especially when I do crazy, fun things. Yeah, she would live for this character, for sure."

Having Wilde as her director was a "dream come true," Lourd says. "She is so smart, so organized, so humble, so beautiful, so kind. She is everything and more. I want to be her." Being on set was like being on vacation, the actress continues, listing "the day on the yacht" among her favorite days of filming. "We had this amazing house party in Encino that was so much fun. I got to hang out of the car in a fur coat. I don't think there has been one day where I was like, this is whatever."

After the magical, friendship-filled, weeks-long film shoot wraps and when the film opens, Lourd, as well as Feldstein and Dever, hopes everyone who sees their movie goes home with a smile on their face.

"I think anyone can relate to anyone in this movie," Devers promises. "I think there are a lot of women in the film that are going to be your real-life friend. I think that is what Olivia wanted from the very beginning."

"There are so many movies where there would only be an Amy or a Molly. There wouldn't be both," Feldstein says for her part. "Or George and Alan are the two theater kids and it would just be George or it would just be Alan. Or just Jared or just Gigi. The beauty of our film is that you get to see more than one representation of a typical teen."

Lourd, meanwhile, wants the audience to be "crying so hard laughing that they can’t breathe. But I hope they are OK!" After all, Booksmart is hilareal. "It will definitely leave you laughing, but the funniest things are the realest things. My mom used to say, 'If life isn't funny, then it's just true.' And that’s this movie."

Booksmart arrives in theaters on May 24.


Olivia Wilde Wanted to See a Buddy Comedy About Female Friendship, So She Directed One (Set Visit)

Beanie Feldstein Is the Broadway Star-Turned-Movie Star Next Door (Exclusive)

Olivia Wilde on the 'Extraordinary' Response to Her Directorial Debut 'Booksmart' (Exclusive)