This novel seems so childlike and simple that one is tempted to think it carries no theme at all, but that it is rather merely an extremely well-done satire of fairy tale conventions. Welty herself once said that the story came from “a lifetime of fairy-tale reading.” Nevertheless, there are two underlying themes in the work—a cultural one concerning the nature of the inevitably changing American frontier and a psychological one typical of all great fairy tales.

On one level, the story is about the gradual loss of American frontier life; Clement, goaded by his possessive and greedy wife, is a reluctant embodiment of the taming of the wildness of the frontier by the civilizing effect of landowning. The Indians, mysterious and mostly unseen presences in the story, represent both the violence and the innocence of the wilderness; as Clement understands, they know that their time is limited. The central duality of Jamie, who is both a gentleman and a robber, suggests the transition point of the wilderness that the novel attempts to capture, for it takes place at a time in American history which hovers between the freedom of lawlessness and the restraint of civilized society.

Because the story also makes use of fairy-tale conventions as well as those of American folklore, it is not only the innocence, violence, and youth of the country that is depicted but also these same characteristics of the individual, for these are aspects upon which the fairy-tale genre particularly focuses. Thus the youth of America and the youth of the individual are paralleled in the story. Just as this duality dominates the overall story, the tone and the characters of the story also exhibit a duality, for the tale is one of innocence and of violence at the same time. Moreover, just as the characters are caught between their dual selves as well as between the past and the present, so also is the reader caught between fantasy and reality. As is typical of the youth of the nation and the youth of every individual, the two realms of fantasy and reality blend together in such a way that one can never be too sure what realm one inhabits. As Clement says about the duality, “This should keep us from taking liberties with the outside world, and acting too quickly to finish things off.” Thus, the story’s most basic theme has to do with the elusive nature of reality itself, which is chimerical and ever-changing.

Welty's principal theme in The Robber Bridegroom is the duality of experience, the gap between appearance and reality. This is a human concern that spans all times and places; it is a truth verified in history, legend, fairy tale, and myth alike. People and things are not always what they seem to be, and an innocent man like Welty's planter working his way through a dualistic world is bound to suffer. Furthermore, Welty attests through the relationship of her young lovers, the planter's daughter and the bandit-gentleman, that duplicity in human relationship leads to distrust and suffering.

One of Welty's favorite motifs throughout her fiction is the function of memory and the past, usually personal memory. Here, however, she uses history and the collective memory of western civilization — in the form of myth, tale, and legend — to tell her story. Thus, The Robber Bridegroom is different from her other fictions, but then so are most of her fictions different again from each other. Welty is probably one of this century's most versatile writers of fiction, using a wide variety of forms and methods to explore the self's deepest needs as these needs confront community expectations and imperatives. At the heart of all her work, however, is storytelling. She is a master storyteller, and she writes about people who live by the story. But while her other fiction is full of stories and the ritual of mythmaking in communities, The Robber Bridegroom takes existing myths and reveals the large fabric of human truth behind them.