Adam is a gentle man who desires peace and a secure family life. After inheriting a fortune from his father, he moves to the Salinas Valley in California to cultivate his own personal garden of Eden. His trusting nature makes him vulnerable to exploitation, particularly by his wife. He struggles to connect with his twin sons, remaining emotionally distant for much of their childhood.

Charles is Adam's younger half-brother. He is marked by immense physical strength and a prominent dark scar on his forehead. He is a diligent farmer who harbors intense jealousy regarding his father's arbitrary preference for Adam. Despite his aggressive temperament and capacity for violence, Charles maintains a surprisingly honest self-awareness and a complex underlying bond with his brother.

Lee is an American-born man of Chinese descent who works for the Trask household. Highly educated and deeply philosophical, he often affects a stereotypical accent to fulfill societal expectations while quietly observing everything around him. He serves as the intellectual center of the Trask family, offering guidance and actively raising Adam's twin sons.

Samuel is a joyful Irish immigrant with a large family and a poor business sense. He is highly skilled with his hands, frequently assisting his neighbors with practical tasks like well-digging and delivering babies. His warm disposition and rich intellect make him a beloved figure in the community.

Cathy is a remarkably beautiful woman who completely lacks normal human empathy. She uses her charm and sexuality to exploit others for her own security and independence. After arriving battered on the Trask farm, she marries Adam but views the relationship entirely as a matter of convenience and self-preservation.

Aron is one of Adam Trask's twin sons, characterized by his fair hair and universally beloved, innocent nature. He prefers to see the world in idealistic terms, which leaves him ill-equipped to handle difficult realities. He craves purity and stability, eventually turning to religion as a sanctuary from the darker aspects of life in Salinas.

Caleb, often called Cal, is Adam Trask's darker, more brooding twin son. He possesses a sharp intelligence and a natural capacity for leadership. Desperate for his father's affection, Cal actively works to overcome his darker impulses and forge his own identity in the shadow of his brother's effortless popularity.

The narrator is a member of the Hamilton family who chronicles the intertwined histories of the region. He provides historical context, philosophical reflections, and personal memories regarding the families in the valley. His perspective frames the story's exploration of human nature and individual choice.

Liza is Samuel Hamilton's highly conservative and deeply religious wife. She approaches life with strict practicality, believing firmly in the moral value of hard work and suffering. Her stern demeanor balances her husband's joyful, sometimes impractical dreaming as they raise their nine children.

Cyrus is the patriarch of the Trask family in Connecticut. After a brief and unimpressive stint in the military, he fabricates a heroic war record that eventually earns him a prestigious position in Washington, D.C. He runs his farm like a military camp and creates deep rifts between his sons through his obvious favoritism.

Alice is Cyrus's second wife and the mother of Charles. She is a quiet, steadfast woman who hides a mysterious inner life, evident only in occasional secret smiles. She treats both her biological son and her stepson with care, attempting to maintain peace in a tense household.

Abra is a perceptive and independent girl from a wealthy local family. She becomes closely entangled with the Trask twins, initially drawn to Aron's apparent perfection but increasingly aware of his inability to accept reality. She seeks genuine emotional connection and is unafraid to acknowledge her own flaws.

Will is one of Samuel Hamilton's sons who breaks the family cycle of poverty. Possessing a shrewd business mind and a practical attitude, he capitalizes on the rise of the automobile and early twentieth-century commerce to become a wealthy, respected member of the Salinas community.

Tom is Samuel Hamilton's deeply sensitive and passionate son. He is completely devoted to his family, particularly his sister Dessie, but struggles with a restless nature and intense emotional highs and lows. His difficulty finding a stable path in life causes worry for his siblings.

Dessie is a beloved daughter of the Hamilton family known for her warm personality and hearty laughter. She runs a successful business in Salinas but maintains an intensely close bond with her brother Tom, choosing to prioritize her family ties above all else.

Olive is one of Samuel Hamilton's daughters who uses education to escape the poverty of the family ranch. She becomes a dedicated teacher and exhibits fierce patriotism, demonstrating a strong-willed independence typical of the Hamilton children.

Faye is a madam who owns a prominent brothel in Salinas. She is maternal and trusting toward her employees, qualities that leave her dangerously vulnerable when a new, calculating worker arrives at her establishment looking for power and inheritance.

Mr. Edwards is a seemingly respectable Boston businessman who secretly runs a profitable prostitution enterprise. He hires a young Cathy Ames and quickly falls deeply into her manipulative orbit, a relationship that ends in brutal violence when he uncovers her past.

Horace Quinn is a local deputy and later sheriff in the Salinas area. He represents the frontier style of justice where reputation and community stability often outweigh strict adherence to the law. He keeps quiet about town scandals when he feels it serves the greater good.

Joe is a cynical and untrustworthy enforcer shaped by a lifetime of abuse. He learns early to trust no one and works for Kate, though he continually looks for ways to undermine her authority and gain leverage over his employer.

Mr. Rolf is an ambitious local minister who takes a strong interest in guiding young men toward the clergy. He mentors Aron Trask, encouraging his ascetic and highly idealized views on religion and morality.