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LawProse Lesson #111: Why Do Plural Possessives Cause So Much Trouble?

Much confusion surrounds plural possessives. Is it as simple as adding an apostrophe to the final -s? What if the plural noun doesn’t end in -s? How do you form a possessive for units of time? What about joint possessives? The list goes on.

This confusion became apparent when our last LawProse Lesson, on the misuses of apostrophes, generated a few e-mails from readers objecting to our illustration of a plural possessive: The fugitive fled to the Joneses’ house, not the Smiths’. That example is correct. Why is it not “Jones’s house” and “Smith’s house”? Because the fugitive fled to the house of Mr. and Mrs. Jones (the Joneses, plural), not to the house of Mr. and Mrs. Smith (the Smiths, plural). This is a spot-on illustration of the general rule for plural possessives:

When forming a plural possessive, use the word’s standard plural form and add an apostrophe after the final -s.

Pluralize first, then form the possessive. If the fugitive had fled to the house of Mark Jones {Mark Jones’s house} or to the house of Connor Smith {Connor Smith’s house}, then the readers’ objections would have had merit.

Of course, as with most rules, there are nuances. So here are some go-to guidelines for the most common issues that arise with plural possessives:

Irregular plurals — that is, those not ending in -s. Add -‘s just as you would to the singular form {children’s or men’s clothing} {the three mice’s cages}.

Units of time or value. For times or values, follow the general rule and add the apostrophe after the final -s {seven days’ notice} {ten years’ experience} {40 dollars’ worth}. In these examples, the units of time and value are adjectives preceding the nouns notice, experience, and worth. They could also be rendered as fully expressed genitives {notice of seven days} {experience of ten years} {a worth of 40 dollars}. But five months pregnant takes no apostrophe because the main word pregnant (as in pregnant for five months) is an adjective, not a noun.

Nouns ending in -s that are plural in form but singular in meaning. For singular terms that derive from plurals, treat the term as a plural. Just add an apostrophe after the final -s {politics’ impact} {the United States’ influence on commerce} {General Motors’ market share}. Some people try to make it *General Motors’s cars, but this form is both highly pedantic and alien-looking since the singular proper name General Motors is actually formed from a plural.

Joint possessives. To indicate joint possession, add -‘s to just the last element in the series {Strunk and White’s book (Strunk and White are coauthors)}. To signal individual possession, add -‘s to each element in the series {King’s and Taylor’s books (King and Taylor wrote separate books)}.

Acronyms and initialisms. It doesn’t come up often (and it’s easily avoided), but the plural possessive of acronyms and initialisms follows the general rule. Take the singular {an MRI}, make it plural {two MRIs}, and add an apostrophe {the three MRIs’ role in the diagnosis}. If there’s a plural word in an initialism — as when Lloyd’s Register Drilling Integrity Services becomes the singular name LRDIS — treat the full initialism as a singular and make the possessive form singular {LRDIS’s contentions}.

The toughest thing to remember is to pluralize first. Mr. and Mrs. Flowers are the Flowerses (it’s the only plural accepted by recognized grammarians). Their house is the Flowerses’ house. George Flowers’s garden is beloved by all the other Flowerses. And now we see plural possessives in full bloom. If you’re surprised, don’t worry. You’re not alone, and there’s no punishment (such as 30 days’ hard labor).

Garner’s Modern American Usage 644-47 (3d ed. 2009).
The Chicago Manual of Style 353-58 (16th ed. 2010).

Thanks to Carlyn Bishop, Mark W. Dobbins, Jack Edelbrock, Michael J. Linneman, Brendan J. O’Rourke, and Jeanette Bowers Weaver for suggesting this topic.

Bryan A. Garner, President of LawProse Inc., is the most prolific CLE presenter in the U.S., having trained more than 150,000 lawyers and judges. His book — most prominently Black’s Law Dictionary and Garner’s Modern American Usage — have been cited as authority by every state and federal appellate court, including the highest. For more about him, go to To follow him on Twitter: @bryanagarner.

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