Blake Nevius has called The Custom of the Country Wharton's most Balzacian novel. He mentions Balzac's Pere Goriot (1835) and Thackeray's Vanity Fair (18471848) as particular antecedents. Undine Spragg, like Eugene de Rastignac and Becky Sharp, has a greedy, grasping energy, and her adventures reveal a society in which the old orders have become soft and weak.

The Custom of the Country can also be seen as Wharton's contribution to the idea of the "new woman," which had become popular in the novels of Robert Grant, Robert Herrick, David Graham Phillips, and Theodore Dreiser. All these writers created leading female characters who did not automatically accept the subservient, maternal role allotted to women in the popular, sentimental fiction of the day. Undine's reaction to becoming pregnant, her neglect of her child, her need to dominate, and her absorption in herself make her a quintessential "new woman."