Grammar brush-up: Rules for indicating possession with an apostrophe

Having worked with more than my share of tiresome subs who clearly quite enjoy getting their knickers in a twist about other people’s apostrophe crimes, I don’t want to get too snarky about the rights and wrongs of this important little punctuation mark. After all, you can’t blame people for not knowing how to punctuate if they’ve never been taught how to do it. (I tend to agree with the journalism teacher who once told me she could tell a student’s age from their punctuation. Few people under forty have a clue, because they had the misfortune to go to school after it was decided that grammar was too elitist to teach).

But if you care about your business you need to know that you will be judged if you get it wrong.

Ditto if it’s your job to commission signs for a major tax-payer-funded organisation that prides itself on providing young students with a "thrilling learning experience" (urgh, at least two of my most hated words there).


I’m still unsure about whether the very large, open and public-looking door, to which the sign on the left was attached, really is intended for just one Director (as it seems to imply), or several (which seems more likely).

Either way, my confidence in the placement of the apostrophe in the left-hand sign is further undermined by the sign on the right, which appears on the same building. Here, the necessary apostrophe has been omitted altogether.

For those of you who are unsure about what’s wrong with the two signs above, here are twelve apostrophe rules you need to know.

1. Never add ’s to the end of a word just to make it plural (see previous blog post: The apostrophe: a friend for life).

2. One of the main uses of apostrophes is to indicate possession. Possession indicates that something belongs to someone or something – my brother’s wife, the girl’s ball.

3. A phrase is possessive if you can reword it using of or belonging tothe wife of my brother, the ball belonging to the girl.

4. A possessive form of the noun always, always has an apostrophe – the only thing that changes is where you place that apostrophe.

5. To make a singular noun (a word indicating a person, place or thing) possessive, just add ’s at the end, as in the examples given above (my brother’s wife, the girl’s ball). If you're unsure where to place the apostrophe, please don't be tempted to omit it altogether - you'll only look illiterate.

6. Rule 5 applies even if the singular noun already ends in an s – e.g. the bus’s arrival.

7. However, if the noun ends in s because it is plural, add the apostrophe after the s – e.g the boys’ heads.

8. If the noun is plural but does not end in s, add 's – e.g. the children’s mother, women’s clothes (department stores, take note), the mice’s nest.

9. Master the rules above because they will prevent you from being judged by snarky sub-editors.

They'll also enable you to distinguish between the number of people who possess a certain thing and will prevent you from causing confusion in your reader. For example, I saw a sign the other day inviting readers to come to a meeting to hear other peoples’ views. I think the author intended to say other people’s views, because:

other people’s views = the views of other people (individuals) other peoples’ views = the views of other peoples (e.g. the people of China, the people of America)

Other examples:

The boy's head = one boy, one head The boys' head = one head shared by several boys (either they're conjoined twins or the head referred to is the headmaster of their school)

My friends’ wedding = I consider both the bride and the groom as friends of mine My friend’s wedding = I consider either the bride or the groom my friend, but not both

10. The above rules also apply when you're talking about periods of time:

a month's holiday = a singular possessive form so you need to add 's to month

two months' holiday = a plural possessive form so you need to add an apostrophe to months

Ditto one year's time and two years' time, a day's work and ten days' work. You'd be shocked at how many writers' CVs I've seen boasting ten years experience . . .

11. For names that end in s (such as St James's Place and Aristophenes' plays), the rule is simple: use ’s if you pronounce the second s, but just add the apostrophe on its own if you don’t. See previous post.

12. The exception to all of the above is the majority of possessive pronouns, which never take an apostrophe. The following are all wrong: the book is her’s, the house is theirs’, the dog has lost it’s bone. You can leave all these little words in their delightfully unadorned state.

Coming soon: using apostrophes to indicate omitted letters.

Apostrophe archive