Jurgis Rudkus is a hardworking, dedicated Lithuanian immigrant who arrives in Chicago pursuing the American Dream. He honestly believes that America is a land of opportunity, and that if he works hard, he will be able to provide a wonderful life for his family. At first, Jurgis is burly and strong, and he has no trouble finding work. He dismisses the union, and he judges destitute men as lazy. Over time, however, he realizes that the system is rigged against him, and he slowly loses everything: his job, his home, and his family. He realizes that he never could have succeeded; the entire American Dream is a lie. Exploited, desperate, and destitute, he takes up a life of crime, believing that if he can't overcome the corruption, he should become a part of it.
At the opening of the novel, 16-year-old Ona Lukoszaite is a beaming bride, excited to start her new life in America. She is fragile and emotionally sensitive, and she is protected to some extent by her dedicated and strong husband, Jurgis. After being forced to return to work in terrible conditions only a week after giving birth to her son Antanas, however, Ona never recovers, physically or emotionally. After being raped by her boss and forced into prostitution, Ona crumbles. She dies fighting for her life during the complicated labor from a second pregnancy.
Marija is described as a sturdy and bold woman with a nearly unlimited capacity for hard work. She embarked enthusiastically on the trip to Chicago, especially since she had left her farm job in Lithuania after beating up her cruel boss. She is in love with Tamoszius Kuszleika, the fiddler, and the couple would like to marry but never scrape together enough money to do so. Joining the meatpacker's union, Marija earns a reputation as a troublemaker and is eventually unable to find work there. When Jurgis leaves Chicago after Antanas's death, Marija turns to prostitution to support what remains of the family.
As the matriarch of the family, Teta Elzbieta strives to keep their Lithuanian traditions alive. However, her efforts can prove counterproductive, as when she insists that Ona and Jurgis throw a lavish wedding, leading them into debt. She also insists on providing a proper Lithuanian funeral when her youngest son dies and has to beg for money from the neighbors to pay for the priest. When Jurgis finds her and the remaining family near the end of the novel, he discovers Teta Elzbieta has been forced to beg in the streets. In spite of the deprivation her family has suffered, Teta Elzbieta has little interest in socialism, but she agrees to attend meetings with Jurgis as long has he stands by the family.
Teta Elzbieta's eldest son, Stanislovas is forced out of school and into work at a lard factory in order to help the family pay the interest on their new house. After another young coworker loses his ears to frostbite at work, Stanislovas becomes so emotionally traumatized that Jurgis must carry him to and from his job each day in the winter; eventually Jurgis beats him each morning to force the boy into the workplace. When Jurgis leaves Chicago to become a hobo, Stanislav loses his job at the factory and eventually finds a job bringing beer to workers in Packingtown. He forms the habit of drinking a bit from each bottle, and one night falls into a deep asleep inside a factory. Locked in for the night, he is eaten by rats. News of Stanislav's gruesome death is one catalyst for Jurgis's conversion to socialism.