Kincaid is the youngest of four brothers and the primary narrator of the family's history in Camas, Washington. He prefers quiet observation to the strict Sabbath school lessons imposed by his mother's church. Rather than engaging directly in the fierce ideological battles that consume his older siblings, he watches and records their disputes while maintaining a deep, protective loyalty to his father.

Hugh is a former minor league pitcher whose athletic career ends abruptly when his left thumb is crushed at the Crown Zellerbach papermill. Stripped of his public identity, he channels his grief into building a three-walled pitching shed in his backyard, where he practices a private ritual he calls "psalmball." He provides a stoic, grounding presence for his children, offering an alternative to the strict religious environment fostered by his wife.

Laura is the matriarch of the Chance family and a devout Seventh-day Adventist. Her strict enforcement of religious rules—including Sabbath observance and dietary restrictions—stems from a childhood marked by an abusive father who suffered from alcohol addiction. She uses her faith as a shield to protect her family from a secular world she views as corrupt, often resorting to aggressive discipline when her sons challenge her authority.

Everett is the oldest of the Chance brothers, characterized by a sharp intellect and a cynical, combative personality. He refuses to accept his mother's religious absolutism, preferring instead to challenge authority figures through debate, satire, and formal essays. As he grows older, his anti-authoritarian instincts draw him into campus activism and the anti-war movement at the University of Washington.

Peter is the second oldest brother, an academically gifted student who processes the world internally. Highly sensitive to conflict and violence, he physically recoils from distressing events, famously fainting in church as a child. He searches for truth outside the rigid doctrines of his home, exploring Eastern philosophies and seeking an ascetic lifestyle over professional ambition.

Irwin is the physically powerful, earnest third brother of the Chance family. Unlike his older brothers, he embraces his mother's Seventh-day Adventist faith without question, operating on a moral code of simple, unquestioning goodness. He demonstrates his selfless nature through impulsive acts of bravery, though his naive faith is severely tested when he is drafted into the military.

Marion is Hugh's mother, an English immigrant who approaches life with scientific rationalism and strict atheism. Having lost her entire family in World War I, she carries a deep cynicism and views the passions of her son's family—both baseball and organized religion—as destructive wastes of time. Despite her caustic exterior, she provides vital financial and practical support to the household.

Gale Q. "Bull" Durham is a salty, seasoned minor league baseball manager who previously coached Hugh in Oklahoma. He functions as an outside mentor to the Chance family, representing an intellectual and philosophical devotion to baseball that exists entirely outside of commercial ambition. He teaches the art of "junk" pitching, emphasizing cunning and adaptability over raw power.

Beatrice is one of the youngest Chance children, a twin who grows up observing the intense ideological battles of her older brothers and parents. To cope with the tension, she and her sister invent a game called "Famous Scientists," allowing them to detach and document their family's behavior objectively. As she matures, she absorbs much of the ambient trauma in the household, leaning increasingly toward her mother's religious rigidity.

Winifred is Beatrice's twin sister, forming the youngest cohort of the Chance family. She navigates the turbulent household by participating in the "Famous Scientists" game, which provides a structured way to process the chaos around her. She maintains a slightly more independent and inquisitive spirit than her twin, occasionally challenging expectations in her own quiet ways.

Natasha is a sharp, critical college student who studies Russian literature. She sees through the performative aspects of the campus anti-war movement and demands intellectual honesty. Her willingness to challenge superficiality makes her a pivotal correspondent for Everett during his ideological and physical journeys.

Linda is a young woman carrying the weight of a highly traumatic family background. She forms a sudden, deep bond with Irwin just as his life is upended by the draft, leading her to seek refuge and stability within the complex dynamics of the Chance household.

Elder Babcock is a leader in the local Seventh-day Adventist congregation. He represents the rigid institutional authority of the church, frequently collaborating with Laura to enforce discipline in the Chance home. His dogmatic approach to morality directly impacts the older boys, particularly through administrative actions regarding the military draft.

Dr. Franken is an eccentric reconstructive surgeon operating a clinic in Portland. He approaches medicine creatively, offering to perform a radical toe-to-thumb transplant for Hugh in exchange for landscaping work at his property, presenting the family with a chaotic but genuine opportunity for healing.

Captain Dudek is a commanding officer stationed in Vietnam. He operates under unwritten, brutal military policies and manipulates the soldiers under his command, using his authority to enact extrajudicial violence that shatters the moral frameworks of those serving beneath him.

Major Keys is the commander of a military psychiatric hospital in California. He uses clinical language to mask institutional abuse, dismissing religious faith as delusion and utilizing heavy sedation and electroshock therapy to control the patients under his jurisdiction.

Grayson is a manipulative con artist operating in India. He preys on vulnerable foreign travelers, using orchestrated chaos and false friendliness to separate them from their belongings and exploit their lack of cultural understanding.