What is a defining relative clause?

A defining relative clause is a clause that identifies which person or thing you are talking about, so the sentence cannot do without it. In The shoes that I ordered have arrived, the clause that I ordered tells you which shoes. Defining clauses take no commas, can use that, and can drop the pronoun when it is the object.

When can I leave out who, which, or that?

When the pronoun is the object of the verb in the relative clause: the film (that) we watched, the woman (who) I met. If the pronoun is the subject of the clause, it has to stay: the film that won the award, the woman who met me. A quick test is to see whether another subject follows the gap; if it does, the pronoun was the object and can go.

Is it who or that for people?

Both are correct in defining relative clauses: the friend who helped me and the friend that helped me are equally standard, with who slightly more formal. Which is not used for people. In non-defining clauses, with commas, only who is possible: My sister, who lives in Cork, is visiting.

What is the difference between which and that?

In defining clauses about things they are interchangeable, and that is more common in speech: the car that / which I bought. In non-defining clauses, marked by commas, only which is possible: The car, which I bought last year, has broken down. Some style guides for American English reserve which for non-defining clauses altogether, but both are correct in a defining clause.

Can I end a relative clause with a preposition?

Yes, and in everyday English it is the normal pattern: the person I spoke to, the chair he was sitting on. The formal alternative moves the preposition to the front and requires whom or which: the person to whom I spoke. Use whichever fits the register, but never use both positions at once.

English grammar · Intermediate

Relative Clauses: Who, Which, That, Whose, Where, and When

Written by Eleanor Whitfield, Lead English Curriculum Editor · Reviewed September 2026

A relative clause is a clause that describes a noun, attached to it with a relative pronoun such as who, which, that, or whose, or a relative adverb such as where or when. A defining relative clause picks out which person or thing you mean (the man who called, the book that I lost) and cannot be removed without changing the meaning. Defining clauses take no commas, allow that, and often drop the pronoun entirely.

The woman who lives next door is a pilot.

who lives next door tells you which woman

What it is

A relative clause lets you pack a whole sentence of information into the description of a noun. Instead of I met a man. The man designs bridges, you say I met a man who designs bridges. The relative pronoun (who) stands in for the noun inside the clause and links the two ideas. When the clause is needed to identify the noun, it is a defining relative clause: the man who designs bridges is a particular man, singled out from all others. Remove the clause and the sentence loses its meaning or becomes vague.

The keys that were on the table have gone. (Which keys? The ones that were on the table. The clause identifies them.)

How to spot it

Look for who, which, that, whose, where, when, or why directly after a noun, followed by a clause with its own verb. If you can ask which one? and the clause answers it, and there are no commas around it, it is a defining relative clause.

the student who asked the question (who for a person, subject of asked)
the film that we watched last night (that for a thing, object of watched)
the town where I grew up (where for a place)
a friend whose car I borrowed (whose for possession)

That is the everyday choice for both people and things in defining clauses (the man that called, the bag that I lost), but it cannot start a non-defining clause, which takes commas and who or which.

Relative Clauses Quick Reference

Relative pronouns and adverbs in defining clauses

Word	Refers to	Example
who	people (subject or object)	the doctor who treated me
whom	people as object, formal	the doctor whom I saw
which	things and animals	the bus which goes to the airport
that	people or things, everyday style	the bus that goes to the airport
whose	possession, for people or things	the author whose book won
where	places (= in which, at which)	the café where we met
when	times (= on which, at which)	the day when it snowed
why	reasons, after the reason	the reason why she left

Common Relative Clauses Examples in English

Defining relative clauses grouped by what they identify, with the job the relative word is doing inside each clause:

Identifying People

The man who fixed our boiler was very quick.: who is the subject of fixed
I have a colleague who speaks five languages.: who as subject; that would also work
She's the teacher that everyone loves.: that as the object of loves; fine for a person
Is he the guy you told me about?: object pronoun dropped, preposition at the end

Who and that are both standard for people in defining clauses; which is not.

Identifying Things

This is the book that changed my mind.: that as subject: cannot be dropped
The phone which I bought last year has died.: which as object; that or nothing would be more natural
The email you sent never arrived.: object pronoun dropped
There are things which money can't buy.: which as object of buy

In defining clauses, that is more common than which for things, especially in speech.

Places, Times, and Reasons

That's the restaurant where we had our first date.: where replaces at which
I'll never forget the day when we met.: when after a time noun
Is there a reason why you're late?: why after reason
the summer we spent in Greece: when dropped after a time noun

Where and when can often be dropped or replaced by that: the day (that) we met, the reason (that) she left.

Possession with Whose

That's the woman whose dog bit me.: whose dog: the dog belongs to the woman
We visited a village whose name I can't pronounce.: whose for a thing, not only for people
I know someone whose brother works there.: whose links a person to a relative

Whose is always followed directly by a noun; it never stands alone in a relative clause.

How Relative Clauses Work

Five rules that cover the pronoun, its job in the clause, and what you may leave out.

The Pronoun Does a Job Inside the Clause

The relative pronoun is not just a link; it is the subject or the object of the verb in its own clause. In the woman who called me, who is the subject of called. In the woman who I called, who is the object of called and I is the subject. Knowing which job the pronoun has decides whether you can drop it and whether whom is possible.

the woman who called me / the woman who I called

who as subject, then who as object

Find the verb, then ask: is who its subject or its object?

Object Pronouns Can Disappear

When the relative pronoun is the object of its clause, defining relative clauses usually leave it out altogether, especially in speech: the film we saw, the people I work with, the house she bought. A subject pronoun can never be dropped, because the clause would have no subject: the man who called cannot become the man called.

the film (that) we saw / the man who called

object pronoun optional, subject pronoun required

Object pronoun: optional. Subject pronoun: required.

Don't Repeat the Noun with a Pronoun

The relative pronoun already fills the slot that the noun would have taken inside the clause, so nothing else goes there. The book that I read it and the man who I met him both contain an extra pronoun that English does not allow. This error is common for speakers of languages where the relative word is a fixed link and the clause keeps its own pronoun.

the book that I read / the man who I met

no it after read, no him after met

The relative pronoun already fills the slot.

Who, Which, or That

Who is for people, which is for things and animals, and that can replace either in a defining clause. In everyday English that is the most common choice for things and is very common for people too. Whom is the formal object form for people, and it is required directly after a preposition: the colleague with whom I share an office.

the woman who / that runs the café; the bag which / that I lost

that works for both; who and which are specific

Who = people, which = things, that = either (defining only).

Where and When Replace a Preposition Phrase

The house where I live means the house that I live in; where absorbs the preposition. The same goes for when with times (the year when we met = the year that we met in) and why with reason. If the clause has no preposition to absorb, where is wrong: the house that I bought, not the house where I bought.

the house where I live = the house (that) I live in

where replaces in which; no in at the end

Where = in / at which. When = on / at which.

Common Mistakes with Relative Clauses

Incorrect: The man which lives upstairs is a musician.

Correct: The man who lives upstairs is a musician.

Which is for things and animals; people take who (or that in everyday defining clauses). Using which for a person sounds as if you are describing an object.

Incorrect: This is the book that I told you about it.

Correct: This is the book that I told you about.

That already stands for the book inside the clause, so the extra it doubles the object. English relative clauses never repeat the noun with a pronoun.

Incorrect: The people work here are friendly.

Correct: The people who work here are friendly.

Who is the subject of work, and a subject pronoun can never be left out. Only object pronouns can be dropped: the people (who) I met here.

Incorrect: That's the hotel that we stayed.

Correct: That's the hotel where we stayed.

Stay needs a preposition before a place (we stayed at the hotel), so the clause needs either where, which absorbs the preposition, or that with at kept at the end: the hotel that we stayed at.

Prepositions in Relative Clauses

When the relative pronoun is the object of a preposition, English gives you an everyday pattern and a formal one.

Preposition at the end (everyday English)

Leave the preposition where it would be in a normal sentence, at the end of the clause. The pronoun can be who, that, which, or nothing.

the people I work with: with at the end, pronoun dropped
the house that she grew up in: that plus preposition at the end
the song we were listening to: to stays at the end

Ending a clause with a preposition is standard English in speech and most writing, not a mistake.

Preposition before whom or which (formal)

In formal writing the preposition moves to the front of the clause. The pronoun then has to be whom or which; that and who are impossible after a preposition.

the colleagues with whom I work: with whom, formal
the house in which she grew up: in which replaces where
the issue to which he referred: to which; that would not work here

Never combine the two patterns: with whom I work with repeats the preposition and is wrong.

Quick Check: Relative Clauses

Fill each gap with who, which, that, whose, where, or when, or write no pronoun if the gap can be empty.

1. The woman ___ sold me the car has moved away.

Answer: who / that

subject of sold, so a pronoun is required

2. Is this the film ___ you were talking about?

Answer: that / which / no pronoun

object of about; the pronoun can be dropped

3. I know a shop ___ you can buy vintage records.

Answer: where

a place; where replaces in which

4. He's the boy ___ mother teaches at our school.

Answer: whose

possession: the mother belongs to the boy

5. The email ___ I sent you yesterday had the details.