The main theme of Oliver Goldsmith's She Stoops to Conquer is identity, particularly misrepresented and mistaken identity. Let's look at some examples.

At the beginning of the play, Marlow and Hastings get lost and Tony Lumpkin decides to play a little prank on them and on his stepfather, Mr. Hardcastle, by misrepresenting the Hardcastle home as an inn. The two young men fall for it, and when they arrive at the "inn," they show a side of their identity that is hardly flattering. They snobbishly treat the wealthy, important Mr. Hardcastle like an innkeeper. Needless to say, this does not make him especially pleased.

Constance tells Hastings the reality of things, but they agree to continue to deceive Marlow for fear that he will leave in embarrassment. Marlow is a suitor to Mr. Hardcastle's daughter, Kate, who likes him well enough except for his extreme nervousness around her. Apparently, Marlow never gets a good look at Kate's face, for later he mistakes her as a barmaid.

Kate decides to play that role to see if she can get a look at another side of Marlow's personality, and she certainly does. He flirts and compliments her and even tries to kiss her. Kate's father walks in on that show and is, again, not at all pleased.

Meanwhile, Tony and Constance pretend to flirt with each other to keep Mrs. Hardcastle in the dark about Constance and Hastings's plans to elope. Mrs. Hardcastle falls for the misrepresentation because she has already decided that she wants Tony and Constance to marry, even though they aren't at all interested in each other.

In the end, everything works out. The right couples get together, and everyone's identity is revealed. But the characters have taken a twisted path of deception in the process.