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Relative pronouns are words that introduce relative clauses—clauses that provide additional information about a noun in the main sentence. The most common relative pronouns in English are who, whom, which, that, and whose. These words connect ideas, eliminate repetition, and create more sophisticated sentences. Mastering relative pronouns is essential for moving from basic to intermediate and advanced English proficiency.
Table of Contents
What Are Relative Pronouns?
A relative pronoun is a pronoun that introduces a relative clause (also called an adjective clause). This clause provides more information about a noun or pronoun in the main clause. Relative pronouns serve a dual purpose: they replace the noun to avoid repetition, and they connect the two clauses together.
Without relative pronoun: I met a woman. The woman is a doctor.
With relative pronoun: I met a woman who is a doctor.
The relative pronoun "who" replaces "the woman" in the second sentence and connects the two ideas into one smooth sentence. This is the fundamental function of all relative pronouns.
Complete List of Relative Pronouns
| Pronoun | Used For | Function |
|---|---|---|
| who | people | subject |
| whom | people | object |
| which | things/animals | subject or object |
| that | people or things | subject or object |
| whose | people or things | possession |
| where | places | location |
| when | times | time reference |
Who and Whom
Who (Subject Pronoun)
Who is used for people and functions as the subject of the relative clause. It replaces he, she, or they.
The teacher who taught me English was very patient.
People who exercise regularly tend to be healthier.
The woman who lives next door is a pilot.
Whom (Object Pronoun)
Whom is used for people and functions as the object of the relative clause. It replaces him, her, or them. In modern English, "whom" is considered formal; "who" is often used instead in informal contexts.
The man whom I met yesterday is a lawyer. (formal)
The man who I met yesterday is a lawyer. (informal but acceptable)
She is the person to whom I sent the letter. (very formal)
Tip: To decide between "who" and "whom," substitute he/him into the clause. If "he" fits, use "who." If "him" fits, use "whom." Example: "I met him yesterday" → "The man whom I met."
Which
Which is used for things and animals. It can function as either the subject or the object of the relative clause.
The book which is on the table is mine. (subject)
The car which he bought is red. (object)
She adopted a cat which had been abandoned.
Which is also used in non-defining relative clauses to refer to an entire preceding clause:
He passed the exam, which surprised everyone.
She arrived late, which annoyed the teacher.
That
That is the most versatile relative pronoun. It can refer to both people and things and can function as both subject and object. However, it has specific limitations.
The movie that we watched was excellent. (thing, object)
The person that called you left a message. (person, subject)
Where is the book that I lent you? (thing, object)
Key Rule: "That" can only be used in defining relative clauses. It cannot be used in non-defining (comma) clauses.
✅ My brother, who lives in London, is a doctor.
❌ My brother, that lives in London, is a doctor.
Whose
Whose is used to show possession. It replaces his, her, its, or their and can refer to people, animals, or things.
The man whose car was stolen reported it to the police.
I know a woman whose daughter is an astronaut.
The house whose roof was damaged has been repaired.
The company whose products we use is based in Germany.
Where and When
Where (for places)
Where replaces "in which," "at which," or "to which" when referring to places.
The restaurant where we had dinner was fantastic.
This is the town where I grew up.
The hotel where they stayed was near the beach.
When (for times)
When replaces "in which" or "at which" when referring to time periods.
I remember the day when we first met.
Summer is the season when most people go on vacation.
There are times when I feel completely at peace.
Defining Relative Clauses
Defining relative clauses (also called restrictive clauses) provide essential information that identifies which person or thing we are talking about. Without this clause, the sentence would be incomplete or unclear. Defining clauses are not separated by commas.
The man who stole the painting has been arrested.
I need a car that is fuel-efficient.
Students who study regularly perform better.
In defining clauses, you can use who, which, that, whose, where, and when. "That" is often preferred over "which" in American English for defining clauses about things.
Non-Defining Relative Clauses
Non-defining relative clauses (also called non-restrictive clauses) add extra information that is interesting but not essential. The sentence would still make complete sense without the clause. Non-defining clauses are always separated by commas.
My mother, who is 65, still works full-time.
Paris, which is the capital of France, is famous for the Eiffel Tower.
Dr. Smith, whose research is groundbreaking, will give a lecture.
Critical Rule: You cannot use "that" in non-defining clauses. Always use who, whom, which, whose, where, or when.
When Can You Omit the Relative Pronoun?
The relative pronoun can be omitted when it functions as the object of the defining relative clause. It cannot be omitted when it is the subject.
Object (can omit):
The book (that) I read was fascinating.
The woman (whom) he married is a scientist.
Subject (cannot omit):
The book that is on the shelf is mine. (cannot remove "that")
The woman who called you is my aunt. (cannot remove "who")
In non-defining clauses, the relative pronoun can never be omitted.
Common Mistakes to Avoid
Mistake 1: Using "That" in Non-Defining Clauses
❌ London, that is the capital, is very expensive.
✅ London, which is the capital, is very expensive.
Mistake 2: Using "Which" for People
❌ The teacher which taught me was great.
✅ The teacher who taught me was great.
Mistake 3: Double Subjects
❌ The man who he called is my friend.
✅ The man who called is my friend.
Mistake 4: Missing Commas in Non-Defining Clauses
❌ My sister who lives in Paris is a doctor. (implies I have multiple sisters)
✅ My sister, who lives in Paris, is a doctor. (I have one sister; the clause adds info)
Practice Exercises
Fill in the blank with the correct relative pronoun.
1. The girl _______ won the prize is my neighbor.
Answer: who
2. The book _______ you recommended was excellent.
Answer: that / which
3. She is the teacher _______ classes are always full.
Answer: whose
4. The city _______ I was born is quite small.
Answer: where
5. Do you remember the time _______ we got lost in the forest?
Answer: when
6. The person _______ you should ask is the receptionist.
Answer: whom / who
7. My car, _______ is ten years old, still runs perfectly.
Answer: which
8. The students _______ passed the exam celebrated together.
Answer: who / that
Relative pronouns are powerful connectors that allow you to build complex, information-rich sentences. By learning which pronoun to use for people, things, places, and times—and by understanding the critical difference between defining and non-defining clauses—you will elevate your English writing and speaking to a more advanced level.
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