Why do I need to place the preposition "of" before the possessive pronoun "mine" in this sentence?

A friend of mine.

What would happen if I didn't place it like in the sentence "a friend mine". Is this an attributive case? Are there any other cases like this but using other prepositions?

  • 3
    "A friend mine" has one term to describe it... "wrong".
    – Catija
    Mar 3, 2017 at 22:31

3 Answers 3


Possessives that go after the noun they modify with an "of": (mine, yours, ours, theirs, his, hers, ...) can also be used with linking verbs:

It was mine. ==> It was a book of mine.

It will be yours. ==> It will be a book of yours.

Possessives that go just before the noun they modify (my, your, our, their, his, her, ...) aren't used in the "of" form, except for special cases where adding an extra 's' at the end of the possessive doesn't make sense because it already has an 's' (for example, his), so the same word is used for both roles: (his book ==> a book of his).

Another collection of possessives (mine, yours, ours, theirs, his, hers, ...), which go after the noun they are associated with and using an "of", cannot be used just before the noun unless they are a special dual-role possessive (his). These can also be used with linking verbs, as in "It was mine." ... or ... "It will be yours."


In English we can only have one central Determiner in a noun phrase. Determiners are usually words like a, the, no, some, any, which, my, your, his, her and so forth.

Because we can only have one of these words in a noun phrase we cannot say things like:

  • *a my friend
  • *that your friend
  • *which Bob's friend?

The noun phrases above are all ungrammatical in English, although you can say things like that in many other languages, for example, in Italian. Notice that they all have two Determiners. Also notice that one of the Determiners is a possessive pronoun or possessive noun phrase (my, your, Bob's).

To solve this problem, we often make a longer noun phrase and put the owner or possessor in a preposition phrase after the noun. We usually use the preposition of. So we can make grammatical noun phrases which have the same meanings as the examples above like this:

  • a friend [of mine]
  • that friend [of yours]
  • which friend [of Bob's]?

Here the preposition of is necessary to glue the second noun phrase to the first one. It is not optional. The following noun phrases are all ungrammatical:

  • *a friend mine
  • *that friend yours
  • *which friend Bob's?
  • 3
    "I'm going out with Bob's friend.", "Which Bob's friend?", "The pudgy one."
    – Sean D
    Mar 3, 2017 at 23:41
  • Nice answer, but would be good to have sources to reference.
    – Aaron Hall
    Mar 4, 2017 at 1:55
  • @SeanD Yes, we can do ll kinds of weird and wonderful things when we echo people like that! :-) Mar 4, 2017 at 11:36

The construction "a friend of mine" is known as double genitive and is used to mean that you have other friends, as opposed to "my friend" (you have only one friend, or that person is the one you consider as your friend at the time).

"*a friend mine" is ungrammatical.

Note: The term "double genitive" is used by Quirk in his "Comprehensive Grammar of the English Language." Below is the pertinent extract:

Double genitive

  • 3
    To be clear "my friend" doesn't mean you have only one friend. It just means that person is a friend. But "a friend of mine" doesn't mean you have more than one friend. It's much the same as "my friend".
    – Andrew
    Mar 3, 2017 at 17:22
  • 2
    @Andrew Please notice I said it could mean you have only one friend OR that the person you say is your friend is the one you are thinking of as your friend at the time, even if you have a lot of them. There, "my" combines the definiteness of "the" with the possessive, as opposed to "a friend of mine" (just one of the several ones I have)
    – Gustavson
    Mar 3, 2017 at 17:25
  • People do (wrongly) call "a friend of mine" a 'double genitive', but of is not a genitive case marker and hence there is only one genitive in that example, not trwo.
    – BillJ
    Mar 4, 2017 at 12:01
  • @BillJ One of those people is Quirk. Please see the addition to my answer above. The term "double genitive" properly reflects the combination of the "of"- and the " 's"- genitives.
    – Gustavson
    Mar 4, 2017 at 13:37
  • But Huddleston & Pullum in the more recent Cambridge Grammar claim that Quirk is wrong about this. In "A friend of mine", they analyse "mine" as an "oblique genitive" and the PP "of mine" as simply a complement of "friend". The view taken is that English has only inflectional case and that prepositions are not case markers. English has a great many prepositions and overall their role is very different from that of inflectional case markers.
    – BillJ
    Mar 4, 2017 at 13:51

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