After the argument, Marius becomes disillusioned with the Friends of the ABC. He leaves the group and—facing terrible hardship due to his lack of money—moves into a depressing room in a rundown apartment in the same Gorbeau House where Valjean and Cosette once lived. He lives next door to the Thénardier family, now living under the name Jondrette, but does not yet know about Thénardier's relation to his father. He continues to study law and passes his exams, though he is still forced to live in poverty. Whatever money he can save is not enough to escape his impoverished situation. Even when his grandfather and aunt try to help him, his pride causes him to reject their offers. The narrator believes that poverty will help Marius understand himself and the reality of the world. Marius becomes close friends with Mabeuf, the warden at the church who knew his father and has now fallen on hard times. Mabeuf helps Marius find a job in a book shop.

Marius grows into a "handsome young man of medium height" (512) but remains poor. He attracts a great deal of female attention simply by walking down a street.