SHOULD HAVE AND NOT SHOULD OF

I regularly receive the Modern Language Association newsletter The Source from the MLA Style Center, which I peruse diligently. In the issue of 29 January 2026, an article titled “A Common Mistake: Should of in Place of Should Have” caught my attention. It opens with the statement: “You may have seen people write should of, but that is grammatically incorrect.”

I do not generally encounter such usage, nor do I associate with people who write in that manner. Indeed, contrary to the claim, I cannot recall ever hearing anyone say should of in place of should have. I may be living on the fringes of present-day English, but I find the assertion surprising nonetheless.

The author, Laura Kiernan, suggests that “the mistake probably comes from the fact that should’ve sounds similar to should of when spoken.” Try as I might, however, I cannot hear should’ve as resembling should of.

While the explanation is plausible, pointing out this “mistake” strikes me as somewhat unnecessary for the MLA’s readership.

Correct: They should have left earlier.
Incorrect: They should of left earlier.