The party in Chapter III serves two primary purposes. It advances the novel in terms of plot and character development, and it furthers Fitzgerald's examination of the culture of the Roaring Twenties. Nick continues in his role as observer and narrator. His account of the activities and the behavior of the various party guests captures the excess of the era and its freewheeling assault on the previous conventions of American society. Through Nick's observations, Fitzgerald also incorporates many of the historical references to the Twenties that distinguish the novel in terms of its accurate portrayal of the times. Finally, through Nick's observations, the social distinctions between those of East Egg and those of West Egg, which play such a significant role in the development of the novel's theme, are made clearer.
Gatsby's presence and Jordan's role contribute to the development of plot and character. The mystery of Jay Gatsby is enhanced by his appearance at the party, even as the reader is given a first real look at the man, "an elegant young rough-neck." Jordan's private visit with Gatsby during the party advances the plot, suggesting an as yet undisclosed relationship between them.