Chapter 3 is, in many ways, like Chapter 2, moving from one party to another, encouraging the juxtaposition of the two events. Tom's party and Gatsby's party are quite different, although in some ways alike, encouraging the reader to explore in what ways the two men are also similar. The purpose of Chapter 3 is, also like Chapter 2, to provide essential background, although this time it is Gatsby who is introduced. By inserting the chapter about Tom, Fitzgerald has effectively held off introducing the story's main character, helping to build an air of mystery around him, not unlike the mystery that Nick and the others initially associate with him, and by keeping the reader from meeting Gatsby, Fitzgerald links the reader even more closely to Nick. However, the information is sketchy — later chapters help to round out the picture of him: who he is and where he comes from.
Nick tells of Gatsby's parties, elaborate and grand affairs that attract entertainers, socialites, and even ordinary people. Gatsby is a perfect host, generous and hospitable. In fact, he is courteous to the point of being taken advantage of. People routinely come to his house for the parties, but also to use his boats, his plane, his cars, and so on. Gatsby must not mind all his guests, however, because every weekend continues in the same patterns of excess and opulence as he provides his guests with only the finest food, drink, and entertainment.
Nick, living next door to Gatsby, has been observing the parties at a distance, as a casual observer, but in Chapter 3 he is officially invited to attend one. As he moves from being a spectator to being a participant, Nick is able to provide an informed view of not only what goes on at Gatsby's parties, but also what the partygoers themselves are like. When Nick reveals that he is one of the few invited guests at the party, this little detail tells quite a lot: It signals that in some yet unexplained way, Nick is set apart from the typical party guest. Despite living next door to Gatsby, he has never succumbed to the urge to crash one of the parties (which would have been easy enough to do, given the way in which people come and go from Gatsby's affairs). Perhaps it is Nick's Midwestern roots and their implied propriety that keep him at a distance, but regardless, his sense of decorum shows brightly throughout this scene, helping readers see him as a character with integrity.
