I have some questions about the expression "a friend of mine" and I'm quite confused with it. Actually I have found some threads about this topic but they don't hit my point. I'm not a native English speaker.

General people may interpret that "a friend of mine" is "one of my friends" but it sounds to me like "a friend of my friend" or "my friend's friend" who I may or may not know him/her. I was taught that "mine" is a possessive pronoun and it's used to replace the noun mentioned earlier; for example, This is Adèle's book so the book is hers.

  1. Why "a friend of mine" is not "a friend of my friend"? And why "a daughter of mine" is not "my daughter's daughter" or "my grand daughter"?

  2. Why we use "a friend of mine" instead of "a friend of me" to mean "my friend" but we use "a part of it" to mean "its part"? "Mine" is a possessive pronoun but "it" is an object pronoun.

I probably have read all things people trying to answer the questions but I still haven't found the comprehensive rules yet. Can anyone give the comprehensive rules for using the double-possessive form?

I myself may conclude that: 1. The double-possessive form is used when the personal subject pronoun is used. 2. If the noun indicating that the owner is a person or people, either the double-possessive form or the noun itself is used but slightly different in interpretation. 3. If the possesser is an animal, robot, or any inanimated objects; the objective pronoun or the noun itself should be used.

Anyway, is there any mistakes or leakages in those rules?

so I can say that:

a friend of mine = my friend
a computer of yours = your computer
a house if his = his house
a book of hers = her book
a school of ours = our school
a car of theirs = their car
a part of it (not a part of its) = its part
a shirt of Mary's = Mary's shirt (Mary has many shirts)
a shirt of Mary = Mary's shirt (Mary can either has only one shirt or many shirts)
a wing of a bird = a bird's wing
a leg of a robot = a robot's leg (one of the robot's leg)
an office of an engineer = an engineer's office (one of the or only office(s) of a certain engineer)
an enemy of France = France's enemy (one of France's enemies)

Is that correct?

Thank you for all of your answers. They are very helpful.

  • 4
    Interesting. It took me several readings to figure out what you were asking because to a native speaker "a friend of mine" can only mean "one of my friends" and it's so common that people just say the words without stopping to consider the literal meaning. So I don't know why it's that way- it just is.
    – Jim
    Commented Aug 10, 2012 at 5:35
  • 1
    Possible duplicate of Why do you say “friend of mine” instead of “friend of me”, though the answers here seem to be more solid.
    – RegDwigнt
    Commented Aug 10, 2012 at 8:49
  • Also related (duplicate?) Why is it usually “friend of his”, but no possessive apostrophe with “friend of Peter”?. OP's interpretation here doesn't arise with "friend of me", but for obscure reasons we invariably use a "possessive" inflexion with first person singular. And rarely use it with a more "distant" subject such as "friend of God's" (where the possessive apostrophe seems almost "sacrilegious/impertinent" to me). Commented Aug 10, 2012 at 12:45
  • Just watch the movie Donnie Brasco (has a compeletely different meaning in that context). Commented Aug 10, 2012 at 13:06
  • As I have suggested in a comment on my own answer those are not necessarily direct equivalents. I have edited my answer to include what I hope will give some clarification from another respected authority. Commented Aug 10, 2012 at 16:40

6 Answers 6


This is perhaps best explained by providing the relevant extract from the ‘Longman Student Grammar of Spoken and Written English’:

The double genitive is a special construction in which either the independent genitive or a possessive pronoun occurs in an of-phrase:

This was a good idea of Johnny’s.

There’s a talk by this lady from Boulder who’s a student of Sandy’s.

The woman who owns Harte’s is a friend of ours.

As these examples show, the main noun phrase typically begins with the indefinite article. In fact, the definite article does not normally combine with the double genitive: *the good idea of Johnny’s is unlikely to occur.

The meaning of the double genitive can sometimes be alternatively expressed by other constructions. Thus, a friend of ours could alternatively be expressed as one of our friends.

Here is a further explanation from ‘The Cambridge Guide to English Usage’:

The double genitive seems to serve two purposes:

emphasis. This is the effect of paraphrasing “not Jo’s fault" as no fault of Jo’s, or turning “our friend” into a friend of ours. The double genitive unpacks the phrase and foregrounds the noun rather than the person. In conversational examples such as That book of Bill Bryson’s is his best yet, the construction helps to adjust the topical focus.

clarification. Clearly a painting of Lady Rich’s and a painting of Lady Rich mean different things. The first (a possessive) makes the painting part of Lady Rich’s collection, while the second (technically an objective genitive) says that it is a portrait of the Lady herself. The duplication of the genitive is thus not redundant but clarifies the fact that the first construction is a possessive genitive.

  • For the last bit, Johnny's good idea, Sandy's student, or our friend all seem to work in the same contexts with the same meaning. Commented Aug 10, 2012 at 14:22
  • 2
    @Darthfett: I detect a difference of emphasis. Those with 'of' seem to foreground what follows the 'of'. Those without seem to favour, in these examples, 'good idea', 'student' and 'friend'. In any case, 'This was Johnny's good idea' strikes me as being somewhat improbable. Wouldn't it be 'This was Johnny's great idea'? Commented Aug 10, 2012 at 14:50
  • There doesn't have to be any difference in meaning to allow more than one way to say something. People use different phrases in different circumstances and moods; that's why we have to many we can't count them and can only give rules about them. Commented Dec 31, 2019 at 17:18

Barrie England's answer is useful, but doesn't address

(a) the reason that the double genitive is used

(b) the sum total of the restrictions on its use

I can't begin to answer the first of these points, but have some additional remarks to make about the second:

(1) The Longman Student Grammar of Spoken and Written English says correctly:

As these examples show, the main noun phrase typically begins with the indefinite article. In fact, the definite article does not normally combine with the double genitive: *the good idea of Johnny’s is unlikely to occur.

However, it misses the fact that a specific determiner (of the demonstrative subclass) may be freely used: I think we really should consider that good idea of Johnny's.

(2) Usage is idiosyncratic. We say a friend of mine but an enemy of Britain

Comparison of terms

The double genitive seems to be used more for more intimate / personal relationships than for more distant ones:

A friend / book of mine but Friends of the Earth

A friend of the president's far less common than A friend of the president*

NOT An enemy of France's but An enemy of France.

Comparison of president/president's

There seems to be a grey area:

NOT A friend of the family's but A friend of the family, and

A friend of the Smith's far less common than A friend of the Smiths.

(Non-possessive usage, but for close relationships.)

  • +1 for these further relevant points, but to be fair to the ‘Longman Student Grammar’, it is but a stripped down version of the magisterial ‘Longman Grammar of Spoken and Written English’, which may put more flesh on these bones. Commented Aug 10, 2012 at 9:16
  • 1
    Good points and +1 for them. I took the liberty of formatting examples in blocks and changing your links to NGrams to images of the graphs. The NGrams here appear to be unexceptionable, but please read my criticism of indiscriminate NGram usage in general.
    – Robusto
    Commented Aug 10, 2012 at 11:53
  • Thank you, Robusto - much better formatting. Being a retired maths teacher (does that get me banned from the site?) I'm aware of the many errors accidentally or deliberately achievable from the wrong handling and presentation of statistics. Particularly when quoting numbers of Google hits, one has to be very careful that one is actually sampling the construction one is intending to, and not simply the string. Even looking through the first 100 hits given and finding that say 40% of them are relevant, one can't just say there are 40% of say 9000 hits relevant, as initial bunching often occurs. Commented Aug 10, 2012 at 16:31

Why "a friend of mine" is not "a friend of my friend"? And why "a daughter of mine" is not "my daughter's daughter" or "my grand daughter"?

Because "mine" refers to the speaker, not someone else. "A friend of mine" means my friend just like "a book of mine" means my book. If they were someone else's friend, you'd have to say "a friend of theirs" or something like that.

  • 1
    You're missing the OP's point. In a construction like Jane is Peter's friend, but Lucy is mine, mine behaves like a pronoun, meaning my friend. So why can it not mean my friend in this context? Especially since there is no other context in which mine can me me.
    – Colin Fine
    Commented Nov 9, 2012 at 17:15

This is his book/This book of his ...

The possessive determiner and possessive pronoun forms of his are the same.

This is her book/This book of hers ...

The possessive determiner and possessive pronoun forms of her are slightly different.

This is my book/This book of mine ...

The possessive determiner and possessive pronoun forms of my are significantly different. Both my and mine are used to refer to things associated with the speaker.

If I were talking about my friend’s friend, I would have to state explicitly:

This is my friend’s friend's book/This book belongs to a friend of a friend of mine ...

“Friend’s friend’s” is generally avoided as it can be confusing. “Friend of a friend” is common enough that it has been acronym-ised.)

Its is similar in usage to his in the above example. But its is rarely used as a possessive pronoun.

  • I’d say it belonged to my friend’s friend.
    – tchrist
    Commented Aug 10, 2012 at 13:13

"My book" relates to a specific book belonging to me, possibly the only one I own. "A book of mine" relates to one of several books I own, but this is the particular one of which I'm speaking at he moment. Likewise, "my friend" could imply an only friend. "A friend of mine" generally refers to one of several friends, but the one which is being spoken of at that time. If we expand it, it simply becomes "A friend belonging to me", while "my friend" could also mean "my only friend". I've noticed that it's commonly used when the person being spoken to does not know the person being referred to, and/or when it's inappropriate to reveal their name, so "my friend Joe", but just " a friend of mine".


I'm also so confused with this possessive grammar pattern. How do I say where I am when someone calls me when I'm at a wedding of a friend of my girlfriend? Which is correct?

I'm at a friend's of my girlfriend's wedding.

I'm at one of my girlfriend's friend's wedding.

I'm at the wedding of a friend of my girlfriend's.

I'm at the wedding of a friend's of my girlfriend's.

I'm at a wedding of a friend's of my girlfriend's.

Or something else...... Please answer......


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