When to Use a Comma Before Someone’s Name

In 2000, I asked the Modern Language Association the following question. I received the following reply.

Q: The second example sentence in MLA 5.49 (Appositives) reads:

Jeanne DeLor dedicated the book to her only sister, Margaret.

But the third rule of Strunk and White’s Elements of Style says that “no comma should separate a noun from a restrictive term of identification.” The examples given are Billy the Kid; the novelist Jane Austen; William the Conqueror; and the poet Sappho.

Why, then, do you put a comma before “Margaret”?

A: Because “sister” in that sentence is not restrictive, since Jeanne had only one sister. If Jeanne had several sisters, and the sentence read,

Jeanne DeLor dedicated the book to her sister Margaret.

then the appositive would be restrictive (that is, essential — rather than parenthetical — to the description), and would not be set off by commas.

See MLA 5.50 for other examples of restrictive apposition.

Addendum (6/17/2022): Here’s a nice explainer from the Wall Street Journal’s language column:

Wrong
Britain’s leader Boris Johnson

Right
Britain’s leader, Boris Johnson,

British leader Boris Johnson

British Prime Minister Boris Johnson

Britain’s prime minister, Boris Johnson,