English relative clauses
The short answer
A relative clause adds information about a noun. Defining clauses say which one you mean and take no commas; non-defining clauses add extra detail and sit inside commas. Who is for people, which for things, that for either in defining clauses only, and whose for possession.
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The rule
A relative clause is introduced by a relative pronoun, who, whom, which, that, whose, or by where, when and why. Defining clauses identify which thing is meant and are essential to the sentence, so they take no punctuation. Non-defining clauses add information about something already identified, sit between commas, and cannot use that. The relative pronoun may be omitted only in a defining clause and only when it is the object of its own clause, which is a rule most other languages do not share.
| Form | Structure | Example |
|---|---|---|
| who | peoplesubject or object | the woman who called |
| which | thingsrequired in non-defining | the report, which arrived late |
| that | people or thingsdefining only | the report that arrived late |
| whose | possessionpeople and things | the author whose books sell |
| where / when | place and time | the town where I grew up |
| no pronoun | definingobject only | the film we saw |
Part 1 of 3
Defining clauses
A defining clause narrows down which thing you mean, so it is essential and takes no commas: the students who passed will be contacted. Remove it and the sentence no longer says which students.
In a defining clause you may use that instead of who or which, and you may drop the pronoun entirely when it is the object: the film that we saw, or simply the film we saw. Both are ordinary English.
The flat we looked at has been sold.
Pronoun dropped. It was the object.
The man who fixed the boiler left a card.
Subject, so it cannot be dropped.
Everything that happened was recorded.
That after everything, all and only.
Part 2 of 3
Non-defining clauses
A non-defining clause adds detail about something already identified, and sits inside a pair of commas: my sister, who lives in Leeds, is a vet. Lift it out and the sentence still identifies the same person.
Three restrictions apply. That is not allowed. The pronoun can never be dropped. And which, never that: is used when the clause refers back to the whole previous sentence, he resigned, which surprised everyone.
The Thames, which runs through London, is tidal.
One river, extra detail.
She missed the deadline, which caused problems.
Which refers to the whole clause.
Our office, where I have worked for years, is closing.
Where in a non-defining clause.
Part 3 of 3
Prepositions and reduced clauses
A preposition can go at the end, which is normal English: the person I spoke to, or in front of the pronoun, which is formal, the person to whom I spoke. That cannot follow a preposition at all.
Relative clauses can also be reduced to a participle. The people waiting outside is short for the people who are waiting outside; the report written last year for the report that was written last year. Both are common in writing.
The colleague I share an office with is off sick.
Preposition at the end, everyday.
the conditions under which it was signed
Formal, preposition first.
Anyone arriving late will be seated at the interval.
A reduced clause.
Mistakes to avoid
What learners actually get wrong
My brother, that lives in Oslo, is visiting.
My brother, who lives in Oslo, is visiting.
That is not allowed in a non-defining clause. The commas mark the clause as non-defining, so the pronoun has to be who or which.
The book I read it was excellent.
The book I read was excellent.
The relative clause already contains the object, so the extra pronoun doubles it. This is a very common error among speakers of languages that keep a resumptive pronoun in relative clauses.
The people which live upstairs are noisy.
The people who live upstairs are noisy.
Which is for things. People take who, or that in a defining clause. Which with people is one of the fastest errors for a reader to notice.
The town, where I grew up, has changed.
The town where I grew up has changed.
The commas turn it into a non-defining clause, which claims the town is already identified. Without them, the clause tells the reader which town, usually what is intended.
Now use it
Relative clauses
who, which, that, whose, and when you can drop the pronoun. Reading a rule and being able to apply it are different skills, and only one of them shows up when you speak.
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Questions
Asked and answered
- When exactly can I drop the pronoun?
- Only in a defining clause, and only when the pronoun is the object of that clause. The film we saw works because we saw it; the film that won does not, because the film is the subject. If you can insert a subject after the pronoun, you can drop it.
- Is ending a sentence with a preposition acceptable?
- Yes. It is standard English and always has been. The rule against it was imported from Latin grammar in the eighteenth century and never described real usage. The person I spoke to is natural; the person to whom I spoke is formal, not more correct.
- How does this compare with French relative pronouns?
- French chooses on grammatical grounds, qui for subject, que for object, where English chooses on whether the referent is a person or a thing. And French can never omit the pronoun, which is why French speakers keep it in English where a native speaker would drop it.