Relative Clauses in English Grammar

What is a relative clause?

A relative clause is a subordinate clause that provides additional information about something mentioned in the first part of the sentence.

Relative clauses are introduced by a relative pronoun (that, which, who …) or a relative adverb (where, when …) and can be defining (used without commas) or non-defining (set off by commas).

Learn about relative clauses with Lingolia, then practise using them in the online exercises.

Contents

The doctor who is holding a clipboard works in the ER.

The doctor who is wearing a stethoscope is a GP.

The ER doctor, whose name is Jane, has to work nights, which she doesn’t enjoy.

She sees patients that need emergency care. The reason why they are at the hospital is often very serious.

The GP, whose name is Henry, works office hours. The patients that he treats have milder issues, like allergies and colds.

When to use a relative clause

Use a relative clause when you want to connect two clauses or provide additional information about something without starting a brand new sentence.

Example:
The doctor is holding a clipboard. The doctor works in the ER.
→ The doctor who is holding a clipboard works in the ER.

Defining vs. non-defining relative clauses

There are two types of relative clauses in English: defining and non-defining.

Defining relative clauses

Defining relative clauses (also known as identifying relative clauses, restrictive relative clauses, or integrated relative clauses):

  • provide defining information that is essential to the meaning of the sentence
  • are not set off by commas
Example:
The doctor who is holding a clipboard works in the ER.
without the relative clause, it would be unclear which doctor is meant because there are two doctors in the picture

Non-defining relative clauses

Non-defining relative clauses (also known as non-identifying relative clauses or non-restrictive relative clauses):

  • provide extra information that is not essential to the meaning of the sentence
  • are always set off by commas
Example:
The ER doctor, whose name is Jane, has to work nights, which she doesn’t enjoy.
the main information is that the ER doctor works nights; the sentence would still convey this without the relative clauses

How to form a relative clause

Form relative clauses by placing a relative pronoun (that, which, who, whom, whose) directly after the thing being described, followed by the clause.

A relative clause can refer to a subject, object or an entire clause.

Example:
The doctor who is wearing a stethoscope is a GP. (subject)
The patients that Henry treats have milder issues. (object)
Jane often has to work nights, which she doesn’t enjoy. (clause)

List of relative pronouns

The table below shows the English relative pronouns and how to use them:

Relative Pronoun Use for … Example
that people, animals & things
(defining relative clauses only)		 The patients that have milder issues see the GP.
which animals, things and entire clauses Jane has to work nights, which she doesn’t enjoy.
who people The doctor who is carrying a clipboard works in the ER.
Jane, who is an ER doctor, has to work nights.
whose possession/belonging for people, animals and things The patients whose injuries are serious go to the ER.
The ER doctor, whose name is Jane, has to work nights.
whom people that are the object of the relative clause
(formal contexts only)		 The patients whom he treats experience milder issues.
My doctor, whom I saw yesterday, is pleased with my recovery thus far.

Relative pronouns: quick tips

The quick tips below will help you choose the correct relative pronoun every time:

that vs. who

In defining relative clauses (no commas), that and who are interchangeable when referring to people.

Examples:
The doctor who/that is holding a clipboard is an ER doctor.
The patients who/that have milder issues see the GP.

However, in a non-defining relative clause (with commas), we can only use who for people (not that).

Example:
Jane, who is an ER doctor, has to work nights.
not: Jane, that is an ER doctor, has to work nights.

that vs. which

That and which are interchangeable when they refer to animals and things in defining relative clauses (no commas).

Example:
The medication that/which this patient needs is currently unavailable.

However, in non-defining relative clauses (with commas), we may only use which, never that.

Examples:
The medication, which has some side effects, can be found at the pharmacy.
not: The medication, that has some side effects, …

Note: some sources claim that which should not be used in defining relative clauses, but there is actually no official rule that dictates this.

who vs. whom

Save whom for formal contexts; it is rarely used in everyday English. Use who or that instead.

Example:
The patients whom he treats have milder issues.
→ The patients who/that he treats have milder issues.

Learn more about the difference between who vs. whom over in our section on Confusing Words.

Relative clauses with prepositions

Sometimes the verb in the relative clause takes a preposition (e.g., listen to, deal with, ask for …).

In everyday English, the preposition comes at the end of the relative clause:

Examples:
The patient’s condition, which Henry is unfamiliar with, is very rare.
Over there is the doctor that I spoke to.
The patients that Henry deals with have milder issues.

However, in formal English, the preposition comes first. Compare:

Examples:
The patient’s condition, with which Henry is unfamiliar, is very rare.
Over there is the doctor to whom I spoke.
The patients with whom Henry deals have milder issues.
remember: whom is only for formal contexts

When the relative clause refers to a time, place, or reason, we place the preposition first in formal contexts. In everyday situations, we prefer to use a relative adverb. You can read more about relative adverbs directly below.

Examples:
The hospital at which she works is one of the best.
→ The hospital where she works is one of the best. (relative adverb)

Relative adverbs

We can use relative adverbs (when, where, why) to introduce defining and non-defining relative clauses that refer to a time, place or reason.

Relative adverbs replace the structure preposition + relative pronoun (e.g. at which, on which …).

Example:
The hospital at which she works is one of the best.
→ The hospital where she works is one of the best.
relative adverb where replaces at which

List of relative adverbs

As you can see from the table below, the relative adverbs look the same as question words:

Relative Adverb Use for … Example
when a time
(= in/on which)		 Friday is the day on which Henry does all his paperwork.
→ Friday is the day when Henry does all his paperwork.
where a place
(= in/at which)		 The hospital at which she works is one of the best.
→ The hospital where she works is one of the best.
why a reason
(= for which)		 The reason for which they are at the hospital is often very serious.
→ The reason why they are at the hospital is often very serious.

What is a contact clause?

A contact clause is when we leave out the relative pronoun that, which or who in a defining relative clause that refers to the object of a sentence.

Examples:
The medication that/which he takes has some side effects.
the medication = object of the verb take
The doctor who/that I spoke to was very friendly.
the doctor = object of the verb speak

But be careful! We cannot leave out the relative pronoun when it:

  • refers to the subject of the sentence
Example:
The doctor who/that treated my injury was much friendlier than the other doctor.
not: The doctor treated my injury was much friendlier than the other doctor.
  • is part of a non-defining relative clause (regardless whether it follows the subject or the object)
Examples:
The GP is treating a new patient, who has the sniffles.
not: The GP is treating a new patient, has the sniffles.
The GP, who has had a busy day, is treating a new patient.
not: The GP, has had a busy day, is treating a new patient.

Subject or object?

Not sure how to figure out if the relative clause refers to a subject or an object? Here’s how:

  • relative pronoun + verb = subject
Example:
This is the patient that had a serious injury.
that + verb (had) = the patient is the subject of the relative clause
  • relative pronoun + article/noun/pronoun = object
Example:
This is the patient (that) the doctor treated.
that + noun (the doctor) = the patient is the object of the relative clause
  • exception: whose is followed by a noun, but is always the subject of the relative clause
Example:
The GP works office hours. His name is Henry.
→ The GP, whose name is Henry, works office hours.
his name becomes whose in the relative clause