Mistakes of a Night is an excellent descriptive title that covers the basic action of the play, which features numerous cases of mistaken identity, sometimes encouraged by disguises and intentional deceptions. Oliver Goldsmith may have decided that he needed a different title which would be more intriguing and less general. She Stoops to Conquer encourages the reader to ask who “she” is and what the author means by “stooping.” The paradox it presents about winning from a low vantage point is also a metaphor in which physical movement stands for changing social positions. The new title is also satiric in its own right, as it merges two phrases rather than quotes exactly from a poem by John Dryden. The earlier title, as it remained relevant, became the play’s subtitle.

The “night” refers to the temporal setting of the play, which occurs within a single evening and night. A case of deliberate deception is the inciting factor that leads to several mistakes. Tony’s decision to prank Marlow and Hastings leads them to behave incorrectly and disrespectfully toward Mr. Hardcastle. Kate takes advantage of their error through another deliberate act of deception, adopting the disguise of barmaid. The resolution of the plot also depends on a mistake made by her stepmother, who is fooled into thinking she has traveled some distance rather than going around in circles.

In early 1773, a copy of play by Irish novelist, playwright, and poet Oliver Goldsmith (1728–1774) was submitted to the Lord Chamberlain, the official inspector of plays, for the purpose of obtaining a license to perform the play at the Theatre Royal Covent Garden on March 15, 1773 (She Stoops to Conquer, p. 115, Licenser's copy, The Huntington Library).

There was no title for the play written in the application for the license.

Subsequently, a title, She Stoops To Conquer, was written in the application, and a subtitle, Mistakes of a Night, was also added, but in a different handwriting.

There is also a note on the page, in yet another handwriting, making reference to James Boswell's Life of Samuel Johnson, regarding "the difficulty of finding a title" for the play.

In addition, there's a direct reference to Goldsmith's new comedy—"No name is yet given it"—in a letter written by Johnson to Boswell in February, 1773, a month before the play's first production (Boswell, James. Life of Samuel Johnson, LL.D. New York: Modern Library, 1931).

It appears, then, that in early 1773, Goldsmith was having considerable difficulty giving a title to his new play.

There's an apocryphal story that Goldsmith, having settled on Mistakes of Night for the title, suddenly changed his mind one day before the opening night of the play and changed the title to She Stoops To Conquer.

It might be that Goldsmith had, in fact, settled on Mistakes of a Night for the title of the play, but he remembered, or happened upon, a couplet written by John Dryden, as misquoted by the Earl of Chesterfield:

The prostrate lover, when he lowest lies,
But stoops to conquer, and but kneels to rise.

Dryden wrote,

But kneels to conquer, and but stoops to rise.

There is an earlier version of Dryden's couplet, which actually seems to make more sense—at least in nature, if not as a play title:

The prostrate lion, when he lowest lies,
But kneels to conquer, and but stoops to rise.

It might be, too, that Goldsmith was familiar with Dryden's original poem but transposed the words himself, thinking that She Stoops to Conquer was a much better title than She Kneels To Conquer or She Stoops To Rise.

The mystery can apparently be solved by referring to the playbill (the theater program) from the Theatre Royal Covent Garden dated Saturday, March 13, 1773, two days before the first production of She Stoops to Conquer:

On Monday (Never Performed) a New Comedy call'd The Mistakes of a Night (Covent Garden playbills 1772–1773, No. 132, Kemble-Devonshire Collection, Huntington Library.)

It appears that the apocryphal story might be true!

A question now arises as to which came first ... the title of the play, She Stoops to Conquer, or Kate Hardcastle's related line in act 4 of the play: "I'll still preserve the character in which I stoop'd to conquer."

Perhaps the title of the play had nothing to do with Dryden or anyone else and Goldsmith simply realized that the best title for his play could be found in the play itself.

The subtitle of She Stoops to Conquer alludes to one of the most important events in the play. One night, Marlow and Hastings stay at the Hardcastles' home, believing it to be an inn. This is all part of a gigantic prank pulled on the two young men by the fun-loving Tony Lumpkin. When Marlow and Hastings enter the Hardcastle residence, they immediately start behaving in a boorish, condescending manner toward Mr. Hardcastle, whom they mistakenly believe to be a lowly innkeeper.

Instead of revealing the truth, Kate uses the young men's mistake to her advantage, putting on the guise of a common barmaid to win Marlow's heart. Kate knows that Marlow is painfully shy in the company of women of his own class and can only let his hair down in so-called "low" company. So Kate keeps up the pretense that the Hardcastle residence is an inn in order to get her hooks into Marlow. For her, the "mistakes of a night" prove to be fortuitous indeed.