Actors say “break a leg” because wishing someone good luck before a show is considered bad luck, so they wish them something terrible instead. The odd part is the date. The phrase is not an old theater tradition from Shakespeare’s day. Its first recorded use comes from 1921, from horse racing, and the first clear stage use found so far is from an American newspaper in 1948.
First, the racecourse
The language historian David Wilton, who traced the phrase for his site Wordorigins, found its earliest record in a 1921 essay by the Irish writer Robert Wilson Lynd, “A Defense of Superstition”. Lynd was writing about the stage but took his example from racing:
“The stage is, perhaps, the most superstitious institution in England, after the race course. The latter is so superstitious that to wish a man luck when on his way to a race-meeting is considered unlucky. Instead of saying ‘Good luck!’ you should say something insulting such as, ‘May you break your leg!'”
A broken leg would be a disaster for horse or rider, which makes it a natural choice for a reverse wish.
A German hunting phrase?
Wilton points to a possible source, though he calls it “by no means certain”: the German wish Hals- und Beinbruch!, “[broken] neck and broken leg”. He finds the German phrase in hunting jargon by 1902 and in the theater by 1913.
An American novel of 1925, Faith Baldwin’s Thresholds, links the two languages directly. After a German toast, one character asks if it is an expression used before the chase, and another explains that it would be bad luck and that instead “You say, ‘I hope you break a leg’—or your neck—or some such hope of calamity.” Wilton notes that the Oxford English Dictionary says evidence for the German connection “appears to be lacking”, even though its own first citation is this passage.
Then the theater
Theater use turns up later and in America. In her 1939 memoir A Peculiar Treasure, the writer Edna Ferber describes a dress rehearsal where the understudies in the back row “politely wish the various principals would break a leg”. Wilton points out that this is ambiguous: the understudies may simply be hoping the leads get hurt so they can go on instead.
The first clear stage use he found is in the Charleston Gazette of West Virginia on 29 May 1948: “one actor should not wish another good luck before a performance but say instead ‘I hope you break a leg.'”
It was still not universal. In 1951 the theater critic and columnist Leonard Lyons wrote that Miss Truman, hostess of a charity performance of Guys and Dolls, called “Break a leg” to him as he walked on stage, and that he turned round “in disbelief at what I’d heard”. She had to explain the superstition to him. If a theater columnist had not heard it by 1951, Wilton argues, it was probably not yet widespread among actors.
The stories that don’t hold up
Because the phrase sounds so strange, it has collected explanations. Wilton lists some of the popular ones: that it means bending the knee to bow at a curtain call; that the “legs” are the side curtains an actor passes to take a bow; that it refers to Sarah Bernhardt’s amputated leg; and, most often, that it comes from John Wilkes Booth, who broke his leg leaping onto the stage after shooting President Lincoln. Wilton finds no evidence for any of them. Booth did break his leg, he notes, but “there is no connection between the assassination and the expression of good luck.”
Wilton’s own conclusion is cautious. The phrase may come from racing or German hunting slang, or it may have arisen on its own in American theaters, either to avoid a jinx or as an understudy’s joke. What the record shows clearly is the pattern: people who live by luck, racegoers first and actors later, avoid saying “good luck” and wish disaster instead.
