In the prologue, an adult Negi inspects guavas in a New York grocery store and tells the reader how to properly eat one. She says she had her last guava on the day she left Puerto Rico, and begins her story.
Negi's family comes to Macún, Puerto Rico when she's four years old. One day while Negi helps Papi rebuild the floor in their home, Mami notices that Negi and the board are covered in termites. Mami scrubs Negi clean and chastises her for helping Papi even though she told Negi not to. Negi desperately wants to be a jíbara (country people, usually of indigenous origin), though Mami tells Negi she can't be a jíbara because Negi was born in the city. Though Puerto Ricans celebrate jíbaro art and music, they look down on the jíbaro people themselves. Negi finds this hypocritical.
Mami soon gives birth to baby Héctor and Negi notices that her parents start fighting more. Papi leaves and is gone for days, and Mami accuses Papi of seeing other women. Negi learns that Papi has a daughter, Margie, with another woman. She's thrilled at the possibility of having an older sister, but Papi tells her that Margie's mother moved Margie to New York. Mami gets pregnant again, and Negi starts school.
One day, Mami moves Negi and her siblings to Santurce, a suburb of San Juan. Mami does this whenever she gets tired of Macún or Papi. In Santurce, Negi's classmates call her a jíbara as an insult, and Negi doesn't make any friends. Papi begins visiting around Christmas, though Mami mostly ignores him. Mami gives birth to Alicia, and not long after she forgives Papi and moves back to Macún with him. Negi is thrilled to be home again. She makes a friend, Juanita. Negi and Juanita often listen to Juanita's grandfather, Don Berto, tell them jíbaro stories. When Don Berto dies, Negi and Juanita lead the procession to the cemetery carrying a heavy wreath. The next day, Papi explains to Negi what a soul is and tells her that souls stay in a person's body until the person dies. Negi knows Papi is wrong, because her soul often walks beside her.
The following year, Mami has another baby, Edna, at the end of April. When it starts raining the week after, Mami tells her children to undress and play in the rain for good luck. Negi's new teacher, Miss Jiménez, tells the class that the new community center will be offering the children breakfast and putting on a meeting where experts will talk to their mothers about proper hygiene and nutrition. Mami, Negi, and the children go to the meeting, and Negi is upset that Mami makes her watch her siblings outside instead of letting her attend the meeting. Several days later, Negi wakes up and finds a tapeworm wiggling in her panties. Mami gives all the children laxatives, figuring that they all have worms. The school starts a vaccination program and a classmate introduces Negi to the word "imperialist" and the insult "gringo." He tells her that politicians are offering breakfasts and vaccines so that the children's fathers will vote for them in the upcoming election. When Negi asks Papi about this, he explains the words to her but tells her to not use them. Negi doesn't like any of the breakfasts at the community center and finally reaches a breaking point when they serve peanut butter in warm milk. Negi gets sick for days and by the time she returns to school, the elections are over, along with the breakfasts.
One Sunday, Mami dresses Negi up and Papi takes her to Abuela's house to spend a week. They stop in a market to get food and Negi learns the word jamona, which means spinster. Papi assures Negi that she'll never be jamona. When he leaves Negi at Abuela's house, Negi realizes that Papi is using her as an excuse to see another woman, and she feels angry. That night she wonders if Papi doesn't truly love her family. She starts crying, but slams her fingers in a door so she won't have to explain her tears to Abuela. Abuela teaches Negi to crochet later that week, and Negi loves learning. On Sunday, Abuela takes Negi to church and tells her to think only good thoughts, which Negi struggles with. Negi waits all day for Papi to come and he never does. Mami, looking very pregnant and very sad, arrives several days later to get Negi. Negi decides it must hurt less to be jamona and alone forever than it does to be continually disappointed by a man.
Negi and her family weather Hurricane Santa Clara in a neighbor's house with their new baby brother, Raymond. The neighborhood experiences financial hardship after the hurricane, and Mami decides to get work in a bra factory. Gloria, a neighbor girl, helps care for Negi and her siblings, but then she elopes. While Mami is unable to work, she and Negi visit Doña Lola's house often, where Negi and Doña Lola's son, Tato, secretly look at each other's genitals. One day when Negi has had enough of their arrangement and pulls up her panties, Tato tries to grab her. Negi kicks him in the crotch. Mami drags Negi home and beats her with a frying pan. Gloria returns to Macún soon after, and Mami goes back to work. Gloria explains menstruation and where babies come from to Negi, and Negi is disturbed to learn about human sex.
Negi's family begins to attract negative attention because of Mami's job, and Papi dislikes the fact that Mami works. Mami insists that they need the money and soon asks Negi to take on more responsibility for caring for her siblings. Negi tries, but as a child herself she struggles to imitate her mother's authority. During this time Negi envies her cousin Jenny, a spoiled only child. One day, Negi’s sister Delsa comes home and says that Jenny is giving kids rides on her new bike. Negi runs to gather her siblings, but Jenny insists on giving little Raymond a ride. Negi is unable to control her siblings and goes home alone, though she runs back when she hears screams of pain and terror. Raymond and Jenny have fallen, and Raymond's foot got caught in the bike chain. Negi feels responsible, but is later furious when the adults blame Jenny. Not long after Raymond's accident, Mami moves the children back to Santurce, to a neighborhood called El Mangle.
El Mangle floats on a lagoon filled with sewage. Negi gets up the first morning and Mami shows her how to use the bathroom, which is nothing more than a hole cut into the floor. Negi panics when she tries to use this toilet and Mami and Doña Andrea, the woman they're staying with, laugh at Negi. Negi punches Mami for laughing. Mami eventually enrolls Negi in school. Negi hates her teacher, Señora Leona, because she's mean and insists on speaking only in Spanish. Señora Leona calls Negi jíbara as an insult.
One morning, Mami asks Negi to do something very special: close a dead baby's eyes. Negi hesitantly agrees. The experience is terrifying and Negi scrubs herself afterwards. A few days later, Negi and Señora Leona have an altercation in class, but Papi miraculously appears and saves Negi. Papi convinces Mami to move to an apartment in Santurce behind a bar. Raymond's foot refuses to heal, and Mami vows to find him a specialist. After Christmas, Mami takes Negi to Tío Lalo's house to stay for a while. At dinner, Negi learns that Mami is going to New York with Raymond to see a specialist. That night, Negi learns from her cousin Gladys that Negi will have to help peel potatoes for her uncle's famous stuffed potato balls. Negi peels potatoes every morning for the next several weeks until Mami returns. Soon after Mami returns, the family moves again and Negi expresses a desire to learn to play piano. Papi arranges for Negi to take lessons with Don Luis. Negi enjoys her lessons and the attention she receives from Don Luis until she realizes that he's trying to look down her blouse at her developing chest. The lessons stop immediately.
Titi Generosa comes to stay with the children, and Negi's siblings torment her. Papi finally takes Negi back to Tío Lalo's house. When Mami comes back from New York to get Negi, she tells Negi that she came home to find the house locked and the kids distributed among relatives. As Mami and Negi walk to the bus, men catcall Mami, and Negi is terrified and angry. Mami and Papi move together to a new house near a golf course. Negi gets her own room and spends her time listening to radio soap operas about kind men named Ricardo or Armando, and dreams about loving relationships as she watches her parents fight more and more. Negi's first crush, Johannes, comes to the house one day, but Negi thinks he doesn't compare to the men in her soap operas.
The week before Negi's 13th birthday, Papi tells her that Mami is going to move to New York. Mami confirms, and she and Papi have a horrible fight about the fact that Papi won't marry her. Mami packs her things and a month later, takes Negi, Raymond, and Edna with her to New York. They move into an apartment above Tata, Mami's mother. When Negi starts school, she negotiates with the guidance counselor to allow her to enter eighth grade if she can learn English by Christmas. Negi is perplexed by the social structure at the school: white Americans, Italians, Puerto Ricans, and black Americans fight each other constantly. After two months, Mami and Negi move to a larger apartment so the rest of Negi's siblings can come. Soon after they arrive, Negi starts her period and Mami buys her her first bra.
Mami falls in love with Francisco. Tata hates him, and Mami moves into her own apartment. One day, Negi sits in the window and a truck driver on the street starts masturbating and smiling at her. Negi is confused, especially when the man stops when Negi smiles at him. Mami gets pregnant around the same time Francisco is diagnosed with cancer, and he dies not long after their son is born. Around this time, Negi learns that Papi married someone else. She tries to disown Papi, but Mami won't let her. Chico, Tata's brother, pinches Negi's nipple one day and gives Negi a dollar. Negi buys her first sundae with it. When Mami gets laid off, she takes Negi with her to the welfare office to translate.
When Negi starts high school, she sees a guidance counselor and tells him she'd like to be an actress. He's unimpressed, but helps her prepare for her audition for the Performing Arts School in Manhattan. During her audition, Negi forgets a lot of her English and struggles through her monologue. She fears she'll never get out of Brooklyn.
In the epilogue, Negi returns to the Performing Arts High School ten years after graduation to see her mentor. Her mentor compliments Negi on her audition monologue, and Negi hopes that one day she'll be on the school bulletin board of successful former students.