"new money." During the Gilded Age, members of the "new money" class enjoyed unprecedented wealth and opulent lifestyles, which many "old money"

The Age of Innocence
Old money families came from long lines of wealth that could be traced back centuries. New money families had become newly wealthy due to investments in ventures, like railroad companies or oil.
Old money families looked down upon new money families who they felt were unrefined and not suited to upper-class customs. In the novel, it is clear that the old money families are threatened. This leads to the next theme: social acceptance. Societal acceptance was of the utmost importance, and those that did not adhere to societal rules were looked down upon. It was incredibly important to remain up to date on the customs and norms, and people did whatever was necessary to stay in everyone's good graces.
As Wharton describes it, the social code revolves around “form,” “taste,” and “family.” “Form” spans questions of fashion and it dictates that everyone in high society conform to certain standards of action and dress so that no one particularly stands out from the crowd. However, form seems to explicitly deal only with outward appearances; it is unconcerned with any hypocrisy flourishing underneath.
“Taste” is regarded as presiding over and dictating “form.” Taste seems to deal more broadly with what it is and isn’t proper to do, particularly in matters involving sexual relations. Taste relates to the society’s obsession with innocence; characters cannot let on through any action or way of dressing that they are not perfectly ignorant of everything regarded as taboo. For example, Ellen wears a dress to the opera that is judged to be in bad taste because it’s too low-cut.
“Family” acts as a unifying principle in New York, as people are expected to exhibit loyalty to their relations above all, and the families frequently intermarry, which consolidates loyalties and connections. Families must do their best to keep their members in line with society’s rules, but they must also present a unified front when one of their members does transgress “form” or “taste”—in other words, in the face of scandal. For example, though the Wellands and the Archers don’t entirely approve of Ellen’s way of life, they band together to help her when other families socially reject her.
At the beginning of the book, Archer lives unquestioningly by society’s rules and he even prides himself on his knowledge of how to navigate them. However, throughout the course of the story, Archer begins to doubt the wisdom of these rules. He realizes that they set men and women up for failure in marriage, and that they prevent people from interacting with each other in any sincere or honest way. Overall, social rules make his life dull, monotonous, and dissatisfying. Archer also questions society’s rules in a way that can be considered feminist. He pronounces that women should be free to do as they like without fear of estrangement, and he comes to see the value of divorce. He perceives that society doesn’t allow women to develop as whole people, but instead carves them into its stilted ideal.
Ultimately, Archer is forced to fall back into line with society in order to avoid being a complete scoundrel by abandoning his pregnant wife. Once Ellen leaves, he lives a more conventional life than that he had hoped; he watches society change around him, but mostly declines to participate in these changes. In the last chapter of the book, however, Wharton shows that in Archer’s older age New York society has loosened up, and the new generation is constantly acting in ways that would have been considered unacceptable in Archer’s youth. Wharton suggests that social rules aren’t correct just because they’re traditional, and neither are they set in stone, even if they seem to be. Sooner or later, progress will wipe away the most foolishly constricting customs, even if change comes at the price of innocence.
In these novels Wharton creates the overall message that humans can be blinded by what is expected of us, and when we break free of those expectations, we run the risk of excommunication. This is a concept Wharton finds absurd.