English Grammar, Third edition (2011)

Reference Section

The spelling and pronunciation of possessives

R32 The use of the possessive form of names and other nouns is explained in Chapter 1 (1.211 to 1.221).

R33 The possessive form of a name or other noun is usually formed by adding apostrophe s (’s) to the end.

Ginny’s mother didn’t answer.
Howard came into the editor’s office.

R34 If you are using a plural noun ending in s to refer to the possessor, you just add an apostrophe (’).

I heard the girls’ steps on the stairs.
We often go to publishers’ parties in Bloomsbury.

However, if you are using an irregular plural noun that does not end in s, you add apostrophe s (’s) to the end of it.

It would cost at least three policemen’s salaries per year.
The Equal Pay Act has failed to bring women’s earnings up to the same level.

…children’s birthday parties.

R35 If something belongs to more than one person or thing whose names are linked by and, the apostrophe s (’s) is put after the second name.

…Martin and Tim’s apartment. …Colin and Mary’s wedding.

R36 If you want to say that two people or things each possess part of a group of things, both their names have apostrophe s (’s).

The puppy was a superb blend of his father’s and mother’s best qualities.

R37 When you are using a name that already ends in s, you can simply add an apostrophe, for example St James’ Palace, or you can add apostrophe s (’s), for example St James’s Palace. These spellings are pronounced differently. If you simply add an apostrophe, the pronunciation remains unaltered, whereas if you add apostrophe s (’s), the possessive is pronounced /Iz/.

R38 Apostrophe s (’s) is pronounced differently in different words. It is pronounced

/S/ after the sound /f/, /k/, /p/, /t/, or /θ/.

/Iz/ after the sound /S/, /z/, /ʃ/,/ʒ/, /tʃ/, or /ʤ/.

/z/ after all other sounds.

R39 If you are using a compound noun, you add apostrophe s (’s) to the last item in the compound.

He went to his mother-in-law’s house.
The parade assembled in the Detective Constable’s room.

R40 Apostrophe s (’s) can be added to abbreviations and acronyms in the same way as to other words.

He will get a majority of MPs’ votes in both rounds.
He found the BBC’s output, on balance, superior to that of ITV.
The majority of NATO’s members agreed.