This Side of Paradise chronicles the life of Amory Blaine from his childhood up through his early twenties. Born the son of a wealthy and sophisticated woman, Beatrice, Amory travels the country with his mother until he attends the fictitious St. Regis prep school in New England. He is handsome, quite intelligent though lazy in his schoolwork, and he earns admission to Princeton. Though initially concerned with being a success on campus, after failing a class he gives himself over to idleness; he prefers to learn through reading and discussions with friends than through his classes.
Towards the end of his college career, America enters World War I and Amory dutifully enlists, forgoing his degree. During his time overseas, Beatrice passes away. Upon his return to America, Amory meets the young debutante Rosalind Connage, the sister of his college friend Alec. The two fall deeply in love, but because of his family’s poor investments, Amory has little money, and Rosalind does not wish to marry into poverty.
Despite Amory’s best efforts to earn money at an advertising agency, Rosalind breaks off their engagement in order to marry a wealthier man, devastating Amory. He goes on a three week drinking binge, which is finally terminated by the advent of the Prohibition. Amory’s quest for self-knowledge begins to be realized. He has a short summer romance with the wild Eleanor. Soon after, Alec is caught with a girl in his hotel room and Amory takes the blame.
Amory then discovers that his last close tie, the dear friend of his mother and his father figure, Monsignor Darcy, has passed away. Further, the family finances have left him almost no money. He decides to walk to Princeton and is picked up along the way by the wealthy father of a friend who died in the war. Amory expounds his new socialist principles and then continues to walk to Princeton. He arrives late at night, pining for Rosalind. Amory reaches his hands to the sky and says “I know myself, but that is all–”