By Sydney Bucksbaum
March 13, 2020 at 03:22 PM EDT

After 20 years, Stargirl is finally coming to life.

The beloved YA novel by Jerry Spinelli has been out since 2000, but it's only now that the tale of kindness and nonconformity is being adapted for the small screen on Disney+. And director Julia Hart has the perfect explanation as to why.

"Grace [VanderWaal] had to play Stargirl so we had to wait until she was the right age," she tells EW with a laugh. The young winner of America’s Got Talent season 11 — who became famous for her unique singing voice and ukulele skills — makes her acting debut as the titular Stargirl, the quirky, confident, and kind (to a fault!) new girl who turns Leo's (Graham Verchere) formerly quiet high school upside down with her free-spirited and unconventional ways, and her penchant for school spirit, unique fashion ... and songs.

It's Stargirl's love of singing and performing that excited Hart the most about bringing the book to life from the page to the screen. "As much as a novel can allow you to fantasize about the music and her singing and playing the ukulele, you can’t actually hear it," Hart says. "One of my favorite things about turning it into a movie was turning it into a musical. The original draft of the script wasn’t really musical. We thought it would be such a fun opportunity in terms of adaptation to expand her musical tastes and abilities and how she shares that with so many other people and brings them into the performances so it’s not just her. Musical numbers felt like a great way to show her effect of her gift on the community around her."

Below, Hart details why she signed on to adapt Stargirl into a feature film for Disney+, how she avoided making the main character a manic pixie dream girl, what she changed from the book for the movie, and more.

Dale Robinette/Disney+

ENTERTAINMENT WEEKLY: When did you first read the book?

JULIA HART: I graduated high school when the book came out so I kind of missed reading it when I was younger. The first time I read it was after I had been sent the script two years ago by Disney in the hopes I would want to direct it.

What was it about the book that inspired you to direct the feature adaptation?

The world is such a complicated place. It feels like these days, more than ever. My husband and I have two little kids and we just feel so strongly that it’s our responsibility as artists to put life-affirming, hopeful, positive messages for young people into the world. I read the script and then the book right around when March For Our Lives first happened and I found those young people so inspiring. I wanted to make something that honored how inspiring and special young people are.

What was the most important part of the novel that you wanted to get right in the onscreen version?

What I loved most about the book is how it wasn’t afraid to explore the dark side of kindness, this idea of intent versus impact. So many happy, positive stories about young people don’t even go there. I love that Stargirl wanted to do the right thing but there are consequences if you don’t know the whole story of the people you’re trying to help. I love how she learns and her exploring being someone different than who she felt like she was but also coming back to her true self, that felt exciting and new to me. That was important to me to preserve.

Dale Robinette/Disney+

Was there anything you knew you were going to change from the outset in the film adaptation?

I wanted Stargirl and Leo to have even more backstory than they originally had in the book. In the book, Stargirl is a bit of a fantasy to Leo, so I wanted to give her more depth and more backstory, more specifics about her and her relationship with her mother and her past. The book very much stays in Leo’s perspective and the movie does too for the most part, but I loved giving Stargirl more of a voice and character.

Speaking of how the story is told from Leo's perspective, how did you make sure to avoid Stargirl becoming a manic pixie dream girl?

Just by making sure that I as a woman writing her and directing her and Grace as a young woman playing her gave her the authentic female gaze and female perspective which is not something that any manic pixie dream girl has ever had, which is part of the problem. I like to believe that the movie addresses the trope and then acknowledges to the audience that it’s aware of it and is breaking it by being like, you think you know what this is by looking at it but this is a deep, authentic, aching, curious, brilliant young woman who should be allowed to wear and sing and express whatever she wants. She so strongly believes in being her true self, but like a real person, she falters and gives in to the temptation to fit in and be liked but ultimately at the end of the day can be true to who she is and be her true self. Not to spoil anything, but the fact that she doesn’t play in to the male character’s fantasy of her and cuts her own path means she’s not a manic pixie dream girl – she doesn’t become what the man wants her to be. That was really important to us.

There are so many fun musical performances peppered throughout the movie – what was that like bringing them to life?

It was so fun, it was like my dream. I grew up completely in love with musicals so getting to make one was such a dream. I went in and pitched Disney all of my dream songs for those musical numbers and I couldn’t believe that we got the rights to all those songs. It felt like the truest way to adapt a book that clearly has a love affair with music to a movie. I love “Be True to Your School,” I’ve always loved that song and The Beach Boys. That song popped into my head while reading the book and script because it’s such a Stargirl anthem, about letting your colors fly and being true to your school and being true to yourself.

Dale Robinette/Disney+

Going from your previous movies Fast Color and Miss Stevens to Stargirl, you’re making a career out of stories centered on strong, confident women characters. Has that been a conscious choice?

We just got our Stargirl poster framed and hung it up on our wall next to the Fast Color and Miss Stevens poster and I was like, "I like this collection of posters with strong women on them that are filling our house." I just made my dream project with Amazon, an original script that [my husband] Jordan [Horowitz] and I wrote starring Rachel Brosnahan as a mother on the run with her baby because of the all the mistakes her husband made in his life that she’s having to pay for. That’s the next step in the evolution. I used to be a high school teacher and I’m a mother and a lot of my characters are mothers, but I have such a love for young people and representing them well and authentically so it was cool to be a part of bringing a young woman strong female character to the collection of movies I’ve done. Early on in my career, if someone had asked me if I was only interested in taking on movies about women, my answer would have been yes. The stories I want to tell are all about women. I feel fine about that. [Laughs]

There's obviously still a long way to go when it comes to gender equality behind the camera in Hollywood, so as an accomplished female director, what advice would you give to aspiring female directors who are trying to get their foot in the door?

Just to keep trying. It’s the truth. I do think that things are slowly changing but it is still a lot more lip service than it is people putting their money where their mouth is. We really struggled to get Fast Color out into the world but Amazon bought it as a TV show and said, "What’s the next movie you want to make," and they made my next movie. Big companies like that, Disney hired me at six months pregnant to tell this story about a young woman, I was eight weeks postpartum when I was making this movie and I was terrified. So I do think slowly but surely it’s changing and the best thing to do is just keep putting yourself out there. Make a short film, make a music video, make whatever you can to get your foot in the door and keep pushing it open wider and wider.

Stargirl is now streaming on Disney+.

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