20th Century Women stars Annette Bening, Greta Gerwig and Elle Fanning as three women who teach a teenage boy, the son of Bening's character, about girls, life and love — or at least that's how the logline reads.

"Supposedly, the film is about a boy learning how to be a man from women, but what you really see in the movie is a portrait of these three women and how they got to be where they are," writer-director Mike Mills tells The Hollywood Reporter. Set in Santa Barbara in 1979, the A24 coming-of-age dramedy — which is playing exclusive engagments in Los Angeles and New York — is, like the director's 2010 film Beginners, based on Mills' unconventional upbringing and is described as "a long, detailed thank-you note" to his mother.

Mills, 50, spoke with THR about changing the script after becoming a parent, creating a corresponding '70s radio station and entering the awards conversation for the first time: "It's an unfortunate way to evaluate films."

How do you feel about your passion project's release?

I've been working on it for five years, and it's a trip for me to think people are actually seeing it, that it's not just in my head. It's something I'm currently processing. I've been very moved by the way people, whom I love and really respect, are responding to the movie.

Both 20th Century Women and Beginners are based on your life. Why do you choose to do that, and how did the writing compare?

I use personal material not to make a memoir or something for me and my family but because I feel like it's my best hope of making a good movie. I'm going to have the most information to give you, hopefully, something unique and real about people.

My dad is very happy to be out in the world; he has grandeur to him, and he would love to be in a movie. My mom's a little different; she's a secretive and contradictory person. So writing this film was more of a struggle. I had to have a lot of talks in my head with my mom and almost fight with her about "Do I have permission to do this? Why am I doing this? What am I including? What does it mean?" There's no clear answer. I went back and forth on it, and eventually I said, "Mom, you have been dead since '99; I was 33. I'm like 46 now. There's some sort of relief in your life when you get to do this, and I'm sorry." That's how it went. The goal was never to mimic my mom but to use her to hopefully feed a really great performance to hopefully make a good movie.

Annette Bening in 20th Century Women.
Courtesy of Merrick Morton

Do you feel closer to your mom after making this movie?

It's been described as a love letter to my mother, which almost sounds cheesy. But it really is a long, detailed thank-you note. My mom was 40 when she had me, which was unusual; I didn't know any other mom that old. She was from this other time and felt like a '40s person, like Amelia Earhart was picking me up at the skate park. She just didn't fit in, and I was always trying to explain her to the world and, in turn, the world to her. I love the part of the movie where the boy reads the essay to Dorothea [Bening's character] — I never did anything like that, but as a writer and filmmaker, I loved reading that to my mom's ghost. Watching that come together in the edit felt personally meaningful.

Also, somewhere in the process, my son was born, which changes your whole worldview in a way you can't even explain or understand. So some of the key lines in the movie — about never being able to see my kid out in the world with his friends, for example — come from me as a parent, talking through my mom. I feel like my mom's comrade in parenting now, and I owe that all to my boy, really.

The movie's music library is expansive, as if there should be a playlist of 100 songs somewhere.

There's gonna be! It's like the thing I'm most excited about. It's all in the works right now. I'm making a radio station for the movie that's going to be on the website. It's like a 1979 radio station with four hours of music, and I'm doing little song sets and introducing them. I think I've learned from this movie that I just want to be a DJ.

What was your set like?

I love shooting so much. I love actors so much. I'm the happiest, most in love, best version of myself when I'm shooting. It's like the best moments of my life, and, sadly, it's only like 35 days out of a five-year process. I orientate my whole shoot around performance, so we shoot in order. I don't use a lot of lights. I play music all the time; I have live musicians playing sometimes. I had dance parties first thing in the morning — I had music that represented each character, and if you all dance to that music together, it's a weird way to introduce everyone to each person and each character. I try to make it a playful environment, honoring the luckiness that it is to get to make a movie.

Greta Gerwig, Elle Fanning and Annette Bening in 20th Century Women.
Courtesy of Gunther Gampine

What do you wish you could change about the film industry?

I wish they were cheaper — it'd be easier to make them, and there'd be less at stake. It's also so weird that films end up being in competition with each other. They're such different souls, and you can't really compare them in that way, and yet so much of the industry revolves around that in a funny way. I feel like it's an unfortunate way to evaluate films because they're really specific people's separate journeys and endeavors, and to make them compete with each other just feels really funny to me.

But your film has gathered awards buzz. How do you feel being part of that conversation?

I'm really honored to be considered at all in this group. It's hard to explain how heartening it is — you feel seen — and it's not something I'm going to forget at all. It's my first time, and I don't really know how to understand it, to be honest. I feel so lucky that I just got to make my movie — that's the honest truth. Each of these films are their own cosmos unto themselves, and they were so hard for each person to make, so I feel nothing but brotherhood and sisterhood and sympathy for all those filmmakers. [Moonlight director] Barry Jenkins and I have sort of become friends through seeing each other at all these events. That's the best award for me — I made a friend, a filmmaking comrade. That's really rare, so it's like I already won.