Francie is the central character. Her personality sets the tone for much of the novel. As a young girl, she is bright, keenly observant, and a dreamer. Her family's poverty cannot overshadow the joy she finds in small material pleasures—the neighborhood stores, Flossie Gaddis's dresses, "sheeny" pickles, the Nolan's piano, the conch shell that sits in the living room. She watches and sees everything from her perch on the fire escape or her make-do bed in the front room. Of all the characters in the novel, she is most loyal to Brooklyn and her neighborhood in Williamsburg, and we consistently experiences this place through her consciousness. While Francie does inherit Katie's strength of mind and purpose, she also remains sensitive. As Katie says, she remembers things—the old man's ugly feet, or Joanna's stoning in the street. The reader experiences a vicarious sensitivity for the lives of poor folk through Francie's observations and memories.
Francie's introspective nature leaves her without many friends or companions. This same quality keeps her open and sensitive to her community. The author can establish a sense of place through Francie, because Francie is constantly aware of her surroundings, and wishes to experience even more. She sits on the curb telling herself stories, or watches people from her apartment, or reads.
A Tree Grows in Brooklyn tells the story of Francie's coming of age, and subsequently, her fall from innocence. Growing up, however, does not mean that she becomes jaded by the world. In fact, she learns to value it all the more. Ironically, when America enters the war for the first time, Francie experiences an affirmation of life—she realizes she has to live every minute of every hour the best she can. Indeed, this scene could stand in for the way Francie experiences her coming of age. She realizes on her date with Lee that happiness is not a faraway experience, but the little things in life that people often overlook. The author reaffirms over and over again that Francie is part her father , part her mother. Like her father, she can appreciate beauty. At the same time, she grows more like her mother; when Francie and Katie have differences, it is usually because Francie has learned from her mother to stand up for what she thinks is right. Francie recognizes that Katie favors Neeley and for this reason, Francie consistently tries to win her mother's affections; still, she and Katie are so similar that they never grow as close as Neeley and Katie.
By the end of the book, Francie has a more complex view of her world, but never betrays her home and background. Unlike the nurse administering vaccinations, Francie will never "forget" the people and life she leaves behind.