A friend asked me recently to explain where the apostrophe should go in the phrase my parents house. I realised that this is something I’ve corrected many times when editing manuscripts, so it seemed a good subject for a quick tutorial. Here’s an easy way to work it out.
Ask yourself: How many parents are we talking about? If only one (singular), then the apostrophe goes after the word parent:
my parent’s house
meaning: the house of my parent
But if we’re talking about plural parents—mother and father, two mothers, two fathers, any combination of people playing parental roles!—then the apostrophe goes after the plural s:
my parents’ house
meaning: the house of my parents
In summary, to indicate possession:
add apostrophe + s to a singular term
add apostrophe only to a plural term
Where it gets complicated is when the singular term ends in s. There are acceptable variations here, and it becomes a matter of style rather than a rule. I prefer the recommendation of the Style guide for authors, editors and printers (6th edn, John Wiley & Sons, 2002), which is:
apostrophe + s (i.e. no change to the rule above for a singular term)
Dickens’s novels
meaning: the novels of Dickens
Burns’s poems
meaning: the poems of Burns
For: It’s easy to remember because it’s the same style!
Against: Some people think it looks clumsy.
Feel free to disagree! Here are a couple of alternatives.
Some guides recommend:
apostrophe only
Dickens’ novels
Burns’ poems
For: Some people think it looks neater.
Against: Why complicate things?
Others recommend different styles depending on the number of syllables in the singular term:
more than one syllable: apostrophe only
Dickens’ novels
but
one syllable: apostrophe + s
Burns’s poems
For: I can’t think of one!
Against: It looks inconsistent, and why complicate things even further?
There’s yet another variation involving pronunciation (i.e. whether you sound the s or not), but that, in my opinion, is a highly dubious way of deciding which style to use: not everyone pronounces words the same way. So let’s not even go there.
As with any point of style for which there are variations, what’s important is that you choose one (or follow the style set for you) and use it consistently.
Happy apostrophising!
looking up/looking down 
Apostrophising? You just verbicised a noun!
🙂 As the Macquarie Dictionary has done before me.
How stagnant our language would be if we couldn’t invent words! 😉
Thank you so much for yet another wonderful Quick Tutorial, Amanda!
This lesson in Where does that damned apostrophe go has been invaluable as I’m always second guessing as to where to put it. 🙂
Thanks, Marlish 🙂
It’s a peculiar sort of brain that finds apostrophes exciting, and I’m happy to confess I have one of those peculiar brains! I have more grammar books than are strictly needed and I do love Wiley’s Style Guide. What have you done, Amanda? I’m becoming dewy-eyed over a high comma! My husband once memorably wrote a ‘short story’ about a woman who suffered from ‘apostrophitis.’ He claimed any resemblance to a living person was purely coincidental!
Love it! Mike’s on a winner there, Rashida. Not that we know anyone like that… 🙂
Indeed Louise, our language would be stagnant if not for invented words. Necessity being the mother of invention. Invent where necessary! 🙂
I agree with you both. I make a point of including one or two words of my own invention in every book 🙂 (Hardly anyone ever notices.)
I call people who mis-use apostrophes apostrophers … good article 🙂
Good one, Monique! Thanks 🙂