The protagonist of the novel, Lily Bart, is a beautiful young woman searching for the right husband who will give her the money and status to remain in upper-class New York social circles. While she has a streak of the romantic in her, her primary focus is on the wealth and social status of potential suitors, and she casts aside many options, believing she can do better. The novel follows a two-year period in Lily’s life as she moves from party to party, struggling to stay within the favor of the wealthy while mounting larger and larger debts. Unfortunately, her precarious financial situation forces her to try some risky investing with the help of a married man, which ends up backfiring and resulting in her being cast out of the circles she so desperately wishes to join. When her family rejects her for the same untrue rumors, Lily is forced to join the middle class, working as a hat maker. Her slide into poverty and depression continues, and eventually, Lily takes too large a dose of sleeping medication—perhaps accidentally—and dies in her sleep. Her focus on financial success never allows her to truly consider a marriage to Selden, her truest friend and most ideal match.

Lawrence Selden, a young lawyer, is the only person in the novel who is able to move within the elite social circles and yet view them with the detached scrutiny of an outsider. Not wealthy himself, Selden has a distant relationship to money, believing love and happiness to be found instead of purchased. He is one of Lily’s few consistent friends, always providing lively banter, a shoulder to cry on, and honest advice. Selden’s rational thinking often overpowers his romantic side, and it eventually causes him to realize how much he is in love with Lily—a few hours too late.

George and Bertha Dorset are an extremely wealthy couple trapped in a loveless marriage. Bertha is an obnoxious, manipulative socialite who uses gossip and wealth to get what she wants, including the attention of other men. Initially, Bertha pursues Selden, and later she uses Lily as a distraction for George so she can have an affair with another young bachelor. Bertha then becomes jealous of George’s affection for Lily and spreads rumors that result in Lily’s expulsion from society. In the meantime, George is dragged along through his wife’s escapades, eventually looking for divorce and Lily’s hand in marriage.

The Trenors are another socialite couple who often host large events at their home, Bellomont. Mrs. Trenor is a gossip and spends much of her day fretting over the minutiae of entertaining—which guests are the most desirable to invite, which have been “stolen” by another conflicting event, and which unmarried men and women should be set up together. Gus Trenor looks to other women for the attention his wife doesn’t give him. A notorious flirt, Gus is drawn to Lily, and he uses his financial investment skills and a large sum of his own money in a risky investment for Lily. This money becomes the focal point of the second half of the novel, as Lily commits herself to repaying her debt.

Mr. Rosedale aspires to the social circles of the wealthy. Building his fortune in real estate, Rosedale initially appears as the owner of Selden’s apartment building who catches Lily leaving what appears to be a lover’s meeting with Selden. The path of Rosedale’s rise to financial success and place in society sits in opposition to Lily’s decline and death; while she starts as a member of the inner circles and falls from their graces, he works his way up to a point where he no longer is interested in marrying her. Despite the differences in their social standing by the end of the book, Rosedale is still kind to Lily, and he offers her money when he runs into her after she has lost her hat-making job.