Marieme (Karidja Touré) is a 16-year-old African-French teenager living in a poor Paris suburb. Academically Marieme struggles, which forces her into a vocational track where she will learn a certain trade. Due to her mother's demanding work schedule, Marieme's abusive brother is in charge. On her way out of school, the day she found out about vocational school, she is approached by a gang of girls, Lady (Assa Sylla) who is the leader of the group, and her followers, Fily (Marietou Toure), and Adiatou (Lindsay Karamoh), who ask Marieme if she wants to join them for a day trip to the city centre. They wear leather jackets, gold jewelry, and have pin straight hair. Marieme initially declines but after seeing the girls approached by a group of boys, including her brother's friend, Ismael (Idrissa Diabate) whom she has a crush on, Marieme joins them.
The girls fight, steal, intimidate others but love and support each other. Marieme and the girls grow close and she eventually begins to act and dress just like Lady, Adiatou and Fily. Because of their act of stealing, the entire group of girls pay for a hotel room, steal dresses, drink alcohol, do drugs, dance and lip sync to "Diamonds", by Rihanna, and dance all night long. At the hotel Lady encourages Marieme to ignore her abusive older brother's phone calls and gives her a gold necklace with the name Vic for Victory.
Fighting assists in showing dominance over other groups. Lady sets up a fight with a girl who is a member of their rival group. Unfortunately, Lady is beaten by this girl, and has her shirt torn off which is viewed as a disgrace. Due to her loss, her father cuts all of her hair off and makes her keep her distance from the group. Vic/Marieme, wants to prove to herself, as well as Lady, that she has the power and strength to fight, and win, the battle against their rival. Vic miraculously wins the battle by ripping the girls shirt off, as well as cutting her bra leaving her topless. Both Lady and Vic's brother are incredibly proud of her and approving of her feat.
Afterwards Vic leaves home and starts to work for Abou, a local drug dealer. While working for Abou, Vic lives in an apartment with two male roommates. In order not to be sexualized she binds her breasts and wears loose baggy clothing. When her boyfriend discovers she has been binding her breasts they fight. Afterwards she goes to a party at Abou's place where, despite her dressed down look Abou approaches and tries to kiss her. She tells him no and pushes him away. Vic goes to her boyfriend's place to tell him she's done with Abou and he offers to let her stay at his place and marry her. Vic refuses telling him she doesn't want that kind of life. She attempts to go back home, but despite being buzzed into her building she finds herself unable to go in.
Sciamma's inspiration for the film came from the different gangs of girls she saw around Paris, especially around the Les Halles shopping center and the Metro. Girlhood is her last coming of age film and her goal was to focus on friendship, sorority, and the special bond that is formed between girls. Sciamma is frequently asked why she wrote and directed a film about a gang of young French black girls, seeing that she is white. Celine stated, "I had a strong sense of having lived on the outskirts-even if I am middle-class white girl. I didn't feel I was making the film about black women but with black women-it's not the same. I'm not saying, 'I'm going to tell you what it's like being black in France today'; I just want to give a face to the French youth I'm looking at".
The film's casting process took four months to complete where actresses were scouted from the streets of Paris.
Sciamma intentionally cast black actresses because of her concern over the lack of opportunities for black women in France, saying that she "was shocked by how black people were never on screen [in France]. Very, very few – even in TV. Particularly that age group and women. There are no black actresses famous in France."
The film also made prominent use of the song "Diamonds" by Rihanna. Sciamma shot the scene before securing the rights to the song and had to appeal to Rihanna's management in post-production. After seeing the scene, they agreed to grant her the rights to the usage of the song for a minimal fee.
The film received highly positive reviews from critics. On review aggregator website Rotten Tomatoes, the film has a 95% rating based on 60 reviews. Metacritic reports an 85/100 rating based on 20 critics, indicating "universal acclaim".
The Guardian described the film as "a work of cinematic art." In his review for the San Francisco Chronicle, Mick LaSalle wrote, "Girlhood is about as grim as movies get, but it's showing something real, and Sciamma has a feel for this period of life, the camaraderie, the jokes, the kinds of conflicts, the panic and the hope. Each time Sciamma makes a movie, it’s as if she’s saying, not stridently, but plainly, 'Here’s something real people are going through that you’ve never thought about.' That’s a moral use of film, all the more effective in that Sciamma makes Girlhood entertaining."
Sciamma received both criticism and praise for her decision to use an all black cast of girls.
The New York Times appraises Girlhood in A. O. Scott's review by maintaining the movie's focus on a young woman in an absent society where she is fierce, independent, gentle and intelligent in order to survive what comes ahead. A. O. Scott focuses on the conflict between the conscious Marieme developing towards the fearless Vic and how she combats the stereotypes of what a young woman in her situation is expected to become by transforming her experiences into a future she now controls.