Rashida Jones has a good sense of how directors see her. “I am generally cast as the dependable, affable, loving, friend-wife-girlfriend,” she said. As Ann Perkins on the NBC series “Parks and Recreation” Ms. Jones is the voice of reason among her loopier co-stars Amy Poehler, Nick Offerman and Aziz Ansari. But in her new movie, “Celeste and Jesse Forever,” coming out on Friday, she has the chance to unravel that persona, in wanton fashion. She stars as Celeste, who is in the midst of a lingering divorce from Jesse (Andy Samberg).


In her screenwriting debut, Ms. Jones, 36, wrote the comedy with the actor Will McCormack, who plays her buddy on screen; they relied on their own relationships as fodder. (“We dated for like two weeks,” she said, “and then after a slight adjustment, we became friends.”)


“Celeste and Jesse,” directed by Lee Toland Krieger, was made in a tight 23 days for less than $1 million. “We did get an offer from a studio at a certain point — for them to reserve the right to cast somebody else if they felt like I wasn’t financially viable,” Ms. Jones said. After some consideration, she said no. “I felt like this was the only opportunity I had to play this kind of part,” she said, “a character that’s maybe less than likable.”


Last week she spoke by phone from Los Angeles about relationships, feminism and her writerly ambitions. “My pet peeve and my goal in life is to somehow get an adjective for ‘integrity’ in the dictionary,” she said, going on to explain: “ ‘Truthful’ doesn’t really cover it, or ‘genuine.’ It should be like ‘integritus.’ “ Consider it a campaign. Here are excerpts from the conversation.


Q. What made you want to write this now?


A. I wanted to write for a long time, but I had a lot of fear because I have friends who are professional writers, and I felt like, they were that and I wasn’t. I had this idea kind of based on people that I knew. They had purgatory relationships they were into for too long or trying to outsmart the pain of breaking up. I asked Will and we made a pact that we would write every day, and if it was terrible, we would throw it in the trash. We wrote in my backyard, on my couch. I have a couch in my backyard because it’s California. Not rubbing it in.


Q. How did having a writing partner help you?


A. I think the fact that it was for both of us a first attempt at really finishing a screenplay — we were supportive. When you’re by yourself, your critic voice is so loud it’s impossible to get anything done. He and I have had our share of unhealthy relationships with exes. It’s a generational exchange for probably what was your first love 50 years ago. But because we do that delayed adolescent thing, this is the version of first love.


Q. Was it therapeutic, writing this?


A. Very. I was for sure exorcising some demons. I was in a lot of pain when I wrote this movie — life stuff. I understand how people say the artistic process is cathartic.


Q. You were writing around the time of the economic downturn. Did you have trouble getting financing?


A. In 2009 we sold it to Fox Atomic, a subsidiary of Fox. We were like, “This is so easy — how awesome.” And then a month later they folded. And we sold it again to Overture Films, and they closed their assets. About six times that happened. It was frustrating, but I really wanted to make the film. At a certain point my resolve became not that fun for people around me.


Q. Since it’s about Celeste separating from a man, not about her searching for one, did you think about how it fit in the canon of romantic comedies or about subverting those conventions? It seems like we’re seeing more of that on screen.


A. We tried to create an element of surprise: He’s her gay best friend, but he’s not very good at being gay. Women have been interesting forever. I’ve had so many women come up to me and say they were being fully represented, that they’re complex, and it’s O.K. to be complex, and it’s O.K. to be emotional one moment and really pragmatic the next. We’re going through a major evolution, and men haven’t had the same evolution. At some point we’re going to have to do something to bring them along. What are they doing? Get it together! We’re going to have an entire generation of smart, stable successful women go without men, because they’re just playing video games and dating younger girls.


Q. There is the Apatow dude posse of films. Do you feel like you’re part of a lady comedy crew with people like Amy, Maya Rudolph and Kristen Wiig?


A. I will definitely let you say that I’m a part of that comedy crew. Amy’s one of my closest friends. For her it’s important that our relationship on the show reflects the positive, supportive arc that women have for each other. We don’t have conversations about women in film and television and what that means because, honestly, you talk about dynamics and people and the things that interest us, and that probably translates into the things that we write. I think there’s just an inherent burden of being alive and being a woman. No man would ever admit that, but I think women know it, which is: You know more than men, you know more than most people you’re dealing with every day, and you know that’s it up to you to make things move forward, and you get paid half as much, but you just do it. But it works out, because if you can figure out how to harness that femininity — there’s something we have that’s so mysterious to men — that if you can figure out how to use that, you’re good to go.


Q. On that note, let’s talk about one of the funniest moments in the movie, when you and Andy take vegetables and other spherical objects and — how can we say it? — get bawdy with them.


A. Pleasure? Have our way with a ChapStick tube? Will and I [masturbate] vegetables when we write together. We go to the farmers market, and we target innocent vegetables and bring them home with us. We do it when we’re bored. It’s pathetic. So why don’t we share that with the world?