Francie is an imaginative, observant 11-year-old girl growing up in poverty in Williamsburg, Brooklyn. She reads ravenously, working her way through the local library's collection in alphabetical order, and finds beauty in the small details of her environment. Despite the harsh realities of her neighborhood, she remains hopeful and demonstrates deep resilience as she barters with local merchants and cares for her younger brother.

Cornelius "Neeley" Nolan is Francie's younger brother and the favored child of their mother. He shares his father's blond, curly-haired good looks and natural musical inclination, often playing baseball in the neighborhood with his friends. He relies on Francie for companionship but also asserts his independence by pushing her away when other boys are around.

Katie is Francie and Neeley's beautiful, dark-haired mother who works as a janitress to secure a rent-free apartment. Recognizing her husband's unreliability, she becomes the stern, practical foundation of the family, determined to save pennies and ensure her children receive an education. Her pragmatic approach to survival often distances her emotionally from Francie.

Johnny is a handsome, charming, and highly imaginative singing-waiter. He deeply loves his children and tries to instill a sense of wonder in them, taking them to see posh neighborhoods or organizing ill-fated fishing trips. However, he suffers from severe alcoholism and struggles to hold steady employment, leaving the financial burden of the family entirely on his wife.

Sissy is Katie's oldest sister, an uneducated but highly charismatic woman who works in a rubber factory. She has a controversial reputation in the neighborhood due to her multiple marriages and unabashed flirtatiousness. Despite suffering numerous stillbirths, she remains fiercely maternal, frequently stepping in to care for Francie and Neeley.

Evy is Katie's sister, a practical woman who attempts to bring refinement into her difficult life. She possesses a sharp sense of humor and frequently makes fun of her husband's weaknesses, which strangely keeps their household functioning smoothly. She frequently helps Katie during difficult periods, embodying the "invisible steel" of the Rommely women.

Known locally as the "Honest Cop," Sergeant McShane is an imposing, respected figure in the community. He has a chronically ill wife and has lost many children to consumption. He observes the Nolan family with a quiet respect, particularly admiring Katie's beauty and resilience from a distance.

Ben is a focused, confident high school student who also works for a law firm. He intends to become a governor one day and approaches his education with intense dedication. He tutors Francie and helps her prepare for her exams, offering her a glimpse of academic discipline.

Mary is Katie's mother, a deeply religious and uneducated immigrant with a kind heart. She possesses a firm belief in the power of the American education system and advises Katie to read to her children daily so they can escape poverty.

Thomas is Katie's father, an austere immigrant who harbors a deep hatred for most things. He is abusive to his family, speaking only in German, a language his wife actively prevents her daughters from learning to protect them from his insults.

Willie is Evy's husband, a milk-route driver who lacks confidence and constantly bemoans his lot in life. He relies heavily on Evy's strength to function in society and struggles to control his delivery horse.

Ruthie is Johnny's mother, an Irish immigrant who raised four boys alone after her husband died. She deeply resents Katie, feeling that Katie stole her only surviving son from her.

Hildy was Katie's best friend until Katie purposefully seduced her boyfriend, Johnny Nolan. This betrayal ended their friendship permanently and forced Hildy to watch Johnny build a family with Katie.

McGarrity owns the local saloon and holds a deep fondness for Johnny Nolan. He enjoys listening to Johnny's imaginative stories and eventually provides small jobs to the Nolan children so he can remain close to their family's dynamic.

Lee is a soldier about to leave for World War I. He forms an intense, rapid attachment to Francie during a night of dancing, asking her to pretend to be his "best girl" before he ships out.

Joanna is a young, unmarried mother in the neighborhood. Her presence attracts vicious gossip and physical hostility from the local women, serving as a harsh early lesson to Francie about community cruelty and the treatment of women.