Relative clauses in English

Forms and functions of relative clauses in English grammar

This page looks at standard relative clauses, using the principal relative pronouns who that and which.
For information on nominal relative clauses, and on other relative pronouns or adjectives such as whatever or when or whenever, see part 2 ► Relative pronouns and adjectives

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Relative clauses can cause trouble in English, specially when they begin with less common forms of the pronoun who, such as "whom"? or "whose"?. And there’s another problem: when to use which and when to use that? Here are some clear guidelines to help you.

Clauses with the relative pronoun as subject
Clauses with the relative pronoun as object
The relative pronoun as a possessive
Relative clauses starting with a preposition
More complex structures
Defining and non-defining relatives, and punctuation.
Relative clauses which qualify a whole sentence, not just a noun.
Omission of the relative pronoun
(Extra information for French speakers)

1. Clauses with the relative pronoun as subject

1.1. When the relative pronoun is subject of a clause and refers to a human, the relative pronoun who is generally used.

Examples

The man who lives next door is 99.
I know someone who eats red hot chilli peppers.

Sometimes, who is replaced by that, especially in American English and in spoken language:

Examples

The boy that lost his watch was careless.

However,

The boy who lost his watch was careless.

is also quite possible.

After the antecedent those, who is almost always required:

Those who can swim should go first.

1.2.If the relative is the subject of a clause and refers to an inanimate antecedent, which or that must be used.

Examples

The book that’s on the table is mine.
The book which is on the table is mine.

1.3. IMPORTANT:
Omission:As subject of a clause, the relative pronoun can never be omitted. However, the relative clause can be completely omitted:

Examples

The book is on the table is mine is quite impossible, but
The book on the table is mine is perfectly acceptable.

2. Clauses with the relative pronoun as object:

Even if the relative pronoun is the object of the clause, it still stands at the start of the clause.
When the relative pronoun is the direct object of the clause, and refers to a human, the pronoun used is either whom or that.

Examples

The man whom I saw yesterday is 99.
The man that I saw yesterday is 99.

Alternatively, the relative can be omitted, particularly in spoken language:
The man I saw yesterday is 99.
The relative, whether mentioned or not, is the only object of the clause, and there can be no second object following the verb.
Thus we cannot say or write :
The man whom I saw him yesterday is 99. nor The man I saw him yesterday is 99

Whom is not used very often: that, or omission of the relative pronoun, are much more common.

When an inanimate object is referred to, the same rules apply, except that whom is never used: it is replaced by which.

Examples

The book that I was reading was very interesting, or
The book which I was reading was very interesting, or
The book I was reading was very interesting

are all possible

Omission: when it is the object of the relative clause, the relative pronoun can often be omitted, particularly in written English. as in the last example.

3. The relative pronoun as a possessive

Whose is required with both animate and inanimate antecedents: it is the only derivative of who which can refer to animates and inanimates:

Examples

I know someone whose sister is a nurse.
The man whose car I borrowed is very rich.
I chose the set whose price was reduced.
Whose is that bag over there?
Whose bag is that over there?

4. Relative clauses starting with a prepositon:

4.1. Note how to form relative clauses after prepositions: preposition + which for inanimates or things, preposition + whom for people. Stylistically, this is quite formal. Sometimes, when referring to places or locations, in which can be replaced by where; when referring to time, when is generally preferred to at which (moment / point)

Examples

The man with whom I was talking was angry.
The chair on which I sat down collapsed.
In the town where I was born lived a man who sailed to sea (Beatles: Yellow Submarine)

4.2. If the relative pronoun is omitted, then the preposition must come at the end of the clause. Omission of the relative pronoun in examples like the ones below is actually by far the most common usage in modern spoken English, and is also common in written style.

Examples

The man I was talking with was angry.
The chair I sat down on collapsed.

5. More complex structures:

Examples
5.1 Preposition + possession:

The player on whose skills the match most depended, was the goalkeeper.
It is to my parents, thanks to whose generosity I was able to complete my studies, that I am most grateful.

5.2. Selective possession

The café, most of whose customers had deserted it, had to close.
The writer, the first of whose books had been a bestseller, was a coal miner.
There are several ways to go from London to Scotland , the fastest of which is of course by plane.

6. Defining and non-defining relative clauses.

6.1. A "Defining" relative clause (also called a restrictive or integrated relative clause) is one which is essential for the understanding of a statement.

Example

Protestors who smash windows will be arrested.
Cars which can do 150 miles per hour are pointless.
Cars that can do 150 miles per hour are pointless.

The first example tells us that "protestors who smash windows" will be arrested; but suggests that those who do not smash windows will not be arrested. . The word "protestors" in this example is restricted by the relative clause that defines it.
Commas are not required before and after the relative clause.

6.2. In a non-defining relative clause (also called a non-restrictive relative clause or a supplementary relative clause) , the relative clause is not essential for an understanding of the sentence:

Examples

Protestors, who are mostly aged under 30, want to express an opinion.
Cars, that were invented at the end of the 19th century, have become a vital part of modern life.

In the first of these examples, the question of age is not an essential bit of information.
In the second, it is obvious that it is cars in general, not cars from the late 19th century, that are a vital part of modern life.
The relative clause can be omitted without making the sentence meaningless.
In cases like this, commas are usually required before and after the relative clause.

Compare these two examples:

Examples

6.1. People who eat too much tend to have poorer health.
6.2. Sportsmen, who pay attention to their diet, are not usually over-weight.

6.3. Using that instead of who or which in relative clauses

The relative pronoun that may be used in English, particularly American English, in defining relative clauses.
That cannot replace who or which in non-defining relative clauses.

However use of that instead of who or which in defining clauses is an option, not a rule, and a source of plenty of confusion.
Some grammar books suggest that which or who must be used in defining relative clauses, and that that must be used in non-defining relative clauses, but this is not true, not even in American English, and countless quotes from the best authors demonstrate this.

Don't rely on grammar checkers that come with word-processing software.

Furthermore the grammar-check tool on Microsoft Word can be either confusing or just wrong on this point. When the example above, Cars, that were invented at the end of the 19th century, have become a vital part of modern life. was put through the MS Word grammar checker, the group Cars, that were invented was underlined, and the first "correction" suggested was:

Cars that were invented at the end of the 19th century have become a vital part of modern life ... without commas

In this case, the grammar checker has replaced a perfectly acceptable sentence, with the necessary commas, with a sentence that is grammatically wrong ! Without commas, the relative clause becomes a defining clause, and the sentence now implies that cars from the end of the 19th century are a vital part of modern life, which is clearly not the case.

7. Relative clauses which qualify a whole sentence

Sometimes we use a relative clause to qualify not just a noun or pronoun, but a whole sentence or clause. In such cases, the relative clause is introduced by which,never ~~that~~ or ~~what~~.

Examples

He drank too much, which is why he was sick.
It was raining yesterday, which was a pity.
There aren't enough tables in the exam room, which is rather a problem.

8. Omission of the relative pronoun

This point is dealt with above in the sections 2, 3 and 4 above.
Note in particular the question of omitting the relative pronoun in a prepositional relative clause (point 4).
English grammar books sometimes say that it is bad style to end a sentence with a preposition; but this is just not true. On the contrary, when the relative pronounis omitted in a prepositional relative clause, the preposition must come at the end of the clause, even if this is also the end of the sentence. As stated above, omission of the relative pronoun in prepositional relative clauses is normal style in modern English.

Examples

I hope that this is a page you'll really learn something from.
Our company currently has enough financial reserves to get by with.
The project our team is currently working on is of huge potential significance.

► Continue to part 2 : Relative pronouns and adjectives

9: for French speakers; click here for information on expressing the French relative pronoun "dont" in English..

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