Amory moves into Princeton and meets his roommates, Kerry and Burne Holiday. Together, they try to adjust to their new environment, going to movies and getting catcalled by upperclassmen. Attempting to gain status in the class, Amory first goes out for football, but after an impressive start, is sidelined by an injury. He then joins the newspaper, "The Daily Princetonian." Yet he and Kerry notice that they are still not among the elite of the class. They resign themselves, and decide to just have fun for the remainder of the year.
Amory strikes up a friendship based on talking about books with the avid reader, Tom D'Invilliers. Tom interests Amory in many new authors, and Amory introduces Tom to the social life of the college. World War I begins in Europe but Amory takes little interest in it, concentrating instead on his successes at the newspaper and the Triangle Club, the musical theater group he has joined.
On the Triangle Club's trip across the country, Amory is introduced to a new young American social world. The narrator explains how the old world of the "belle" and her gentlemen callers had been replaced by the looser, more risqué world of the popular daughter, the "P. D.," who drinks, smokes cigarettes and kisses men quite casually. Amory, who is quite handsome, greatly enjoys this scene and is very successful in it.
One such very experienced and attractive P. D., named Isabelle, meets Amory at the Minnehaha Club in Minnesota, and the two fall in love within a day. When Amory returns to Princeton, they maintain a rapturous correspondence of love letters.
Because of his involvement in the newspaper, Amory had become somewhat of an elite man on campus. He plays the social scene well and is admitted into the Cottage, one of the elite clubs on campus. Amory remembers his sophomore spring as one of the happiest times of his life--such as when he, Alec Connage, Dick Humbird, Jesse Ferrenby and Kerry go down to the coast for a weekend. They go with no money and survive by sleeping outside and ridiculously underpaying for nice meals, all the while being drunk and boisterous. Amory idealizes Dick Humbird--the way he walks, talks, and acts--as the paradigm of social grace, even when he learns that Dick comes from "new money" and is not of the old elite class.
Tom and Amory reflect on how much the social world at Princeton has made Tom conventional, and the wild times continue. Amory goes to a party in New York with friends. Upon returning, he discovers that Dick Humbird has crashed the other car and been killed in the accident. After this sobering incident, Isabelle arrives to go to the prom with Amory. The two are very much in love. Amory goes for a visit with Isabelle's family at their estate on Long Island.