Margaret Rose Nolan is a sixteen-year-old Irish immigrant hoping to forge an independent future in the United States. Renaming herself simply "Rose" upon arrival, she brings determination and a desire to avoid the traditional path of early marriage. As the oldest daughter, she feels a strong responsibility to support her household, driving her to seek employment despite her status as an inexperienced new arrival. She demonstrates bravery when searching for work across New York City.

Gussela is an eighteen-year-old factory seamstress and a passionate labor union organizer. As the primary breadwinner for her aging father, she understands the exploitative nature of factory work and fights actively for fair conditions. She takes an interest in Rose, encouraging the new immigrant to stand up for her rights against abusive employers.

Mr. Moscovitz owns a paper flower shop in the city, employing young girls to do piecework. He takes advantage of new, desperate immigrants by paying low wages and exploiting their lack of labor knowledge. He uses his position of power to test personal boundaries and behave inappropriately toward young women.

Maureen is Rose's younger sister, known for her sharp tongue and independent streak. She frequently pushes back against authority figures and her parents' rules, earning reprimands for talking back to immigration officers. Her impulsive nature occasionally causes friction within the family, but she shares Rose's strong desire to remain and work in America.

Margaret is the matriarch of the Nolan family and a highly skilled seamstress. She leaves Ireland reluctantly and struggles to adjust to American customs, holding tightly to her Catholic faith and familiar traditions. Her primary focus remains keeping her family together, causing her immense distress when immigration authorities force a separation.

Michael is the father of the Nolan children who originally believed he could provide a better life for them in America. His plans change abruptly when immigration officials deny entry to his youngest child due to a health condition. He makes the difficult choice to return to Ireland to keep his infant son safe while the others stay behind.

Joseph is the infant son of the Nolan family. An infectious bacterial eye infection, trachoma, prevents him from passing the medical inspections at Ellis Island. His health status directly shapes the trajectory of the entire Nolan family upon their arrival.

Bridget is one of Rose's younger sisters. She remains closely tied to her mother as the family manages their arrival in New York City and faces immediate disruptions to their living situation.

Patrick is Michael's brother, an Irish immigrant who has established a successful life as a local politician in New York. He has assimilated heavily into American culture, abandoning Catholic mass for a Lutheran church. He attempts to balance his Irish heritage with his German-American wife's expectations, often serving as a peacemaker in his household.

Elsa is Patrick's wife, a woman of German descent who views recent Irish immigrants with disdain. She places a high value on appearances and social standing, viewing the Nolan family's arrival as a dirty, embarrassing burden on her household.

Trudy is Elsa and Patrick's teenage daughter. She attends private school and looks down on her immigrant cousins, frequently vocalizing her disgust regarding their clothing, habits, and presence in her home.

Hildegarde is another of Patrick and Elsa's daughters. Like her mother and sister, she resents the Nolans and actively taunts them, eventually provoking a physical altercation with Maureen.

Friedrich is the young son of Patrick and Elsa. He is strictly controlled by his mother, who prevents him from partaking in the Nolans' gesture of gratitude.

Tessa is an Italian immigrant girl whose father was a university professor back in Italy but now works as a janitor. She helps Rose learn the flower-making trade and warns her about Mr. Moscovitz's predatory behavior.

Mr. Garoff is an older Jewish immigrant from Russia whose health and stamina have failed due to poor working conditions. He relies on his daughter to support him and disapproves of her working on the Jewish sabbath or engaging in union politics.

Jacob is a cutter at the Triangle Shirtwaist Factory and a friend of Gussela. He supports the female workers by bringing them practice materials and sneaking past the strict anti-theft inspections at the workplace.

Rose Klein is an outgoing, stylish factory worker who befriends the protagonist. She enjoys dime novels, trips to the nickelodeon, and flirting with boys, representing a more modern, frivolous side of American youth.

Rose Bellini is another friendly seamstress at the factory. Alongside Klein, she helps integrate the protagonist into the social culture of the workplace, sharing books and organizing social outings.

Walter is a young man courting Trudy. His presence in the household during a chaotic moment causes great embarrassment for Elsa and her daughters.

Colleen is an Irish bakery owner who takes pity on a discouraged, job-hunting Rose. She provides her with food and an address for her first potential job in New York.

Leah is an older woman and a member of Mr. Garoff's synagogue. She offers practical care and traditional comfort to the girls and Mr. Garoff when they face sudden difficulties in the city.

Bertha is a worker at the factory who helps orient Rose to the demands of the sewing machines.

Esther is another factory worker who interacts with Rose on the bustling sewing floor.