The Saxon Genitive: Possessive Apostrophe Rules

The Saxon genitive is the English way of showing possession with an apostrophe, as in Anna's book or the boys' toys. It is one of the first structures that trips up learners, because English also has a second option, the of-construction, and the two are not always interchangeable. This guide explains how the possessive apostrophe works, when to choose 's over of, how it behaves with plural and irregular nouns, and what to do with names ending in s. Master it and your English will sound noticeably more natural.

What the Saxon genitive is

The Saxon genitive shows that something belongs to someone or something. You form it by adding an apostrophe plus s ('s) to the possessor: the girl's bag, the dog's lead, my brother's car. With most plural nouns that already end in s, you add just the apostrophe: the girls' bags. The possessor comes first, then the thing possessed, which is the reverse of the of-construction (the bag of the girl)

When to use ’s and when to use of

The old rule that the Saxon genitive is "never used with objects" is too strict. In practice English uses 's far more widely than that, and both forms are often acceptable. The safest guide is by category.

The of-construction is often the more natural choice in these cases, though 's is not wrong in everyday English: with inanimate objects (the door of the car), with long or complex noun phrases (the responsibility of the new project manager), with titles of works (the title of the book), and with places treated as pure geography (the capital of France). The key point is to prefer of in these cases, but not to treat 's as forbidden, since forms like the book's cover and the city's history are completely standard.

The Saxon genitive in the plural

Plurals follow three clear rules.

So a regular plural such as students becomes the students' essays, while an irregular plural such as children becomes the children's games. The only real trap is remembering that irregular plurals (children, women, men, people) take the full 's, because they do not already end in s.
Names and singular nouns ending in s
For a singular name that already ends in s, both Charles's book and Charles' book are accepted; the version with the extra s reflects how it is usually said aloud, "Charles-iz". The same applies to names like James, Chris or the boss: James's car or James' car are both fine, so pick one style and use it consistently.

Common mistakes

Two slips are common. First, putting the apostrophe in the wrong place with plurals: it is the boys' toys (several boys), not the boy's toys, unless there is only one boy. Second, adding only an apostrophe to irregular plurals: it is the children's books, not the childrens' books, because children does not end in s. Getting the noun type right first makes the apostrophe easy