A relative clause is a part of a sentence that gives extra information about a noun. It usually begins with a relative pronoun such as who, which, that, whose, or where. For example, in the sentence The woman who lives next door is a doctor, the relative clause "who lives next door" tells us which woman we are talking about. Relative clauses allow you to combine two short sentences into one longer, more natural-sounding sentence.
Mastering relative clauses will make your English sound more fluent and sophisticated. They are used constantly in both spoken and written English, and understanding the difference between defining and non-defining relative clauses is a key step toward intermediate and advanced proficiency.
How to Form / Structure
A relative clause is placed directly after the noun it describes. The relative pronoun you choose depends on what the noun refers to.
| Relative Pronoun | Used For | Example |
|---|---|---|
| who | people (subject) | The teacher who taught me English was excellent. |
| whom | people (object, formal) | The man whom she married is an engineer. |
| which | things and animals | The book which I borrowed was fascinating. |
| that | people and things (defining only) | The car that he bought is red. |
| whose | possession (people and things) | The student whose essay won the prize is my friend. |
| where | places | The restaurant where we had dinner was lovely. |
| when | times | I remember the day when we first met. |
Defining vs. Non-Defining Relative Clauses
There are two types of relative clauses, and they behave very differently:
Defining relative clauses (also called restrictive) identify exactly which noun we mean. They are essential to the meaning of the sentence. No commas are used.
- The students who passed the exam will receive certificates. (only the students who passed, not all students)
Non-defining relative clauses (also called non-restrictive) add extra information that is not essential. The sentence would still make sense without them. They are always set off by commas.
- My brother, who lives in London, is visiting us next week. (extra information; I only have one brother)
Critical rule: You cannot use "that" in non-defining relative clauses. Use "who" for people and "which" for things.
When to Use
Combining Two Sentences
Relative clauses let you avoid repetitive, choppy sentences:
- I met a woman. The woman works at Google. → I met a woman who works at Google.
- She bought a dress. The dress was on sale. → She bought a dress that was on sale.
Giving Essential Identifying Information (Defining)
- The man who called you left a message. (Which man? The one who called.)
- The hotel where we stayed was near the beach.
- The email that I sent you contains the details.
Adding Extra Information (Non-Defining)
- Paris, which is the capital of France, attracts millions of tourists every year.
- My neighbor, whose dog barks all night, finally hired a trainer.
- Our meeting, which lasted three hours, was very productive.
Omitting the Relative Pronoun
In defining relative clauses, you can omit the relative pronoun when it is the object of the clause:
- The movie (that/which) I watched last night was great. ("I" is the subject; "that/which" is the object — can be omitted)
- The person (who/that) you met yesterday is my cousin.
You cannot omit the pronoun when it is the subject of the clause:
- The woman who called me was very polite. (cannot remove "who")
Common Mistakes
| Wrong | Correct | Explanation |
|---|---|---|
| The man which helped me was kind. | The man who/that helped me was kind. | Use "who" or "that" for people, not "which." |
| My sister, that lives in Paris, is a chef. | My sister, who lives in Paris, is a chef. | Do not use "that" in non-defining clauses. |
| The book who I read was good. | The book which/that I read was good. | Use "which" or "that" for things, not "who." |
| The student whose failed the test was sad. | The student who failed the test was sad. | "Whose" shows possession; "who" is the subject pronoun. |
| The city where I was born it is beautiful. | The city where I was born is beautiful. | Do not add an extra pronoun ("it") after the relative clause. |
Practice Examples
Combine each pair of sentences using a relative clause:
- I have a friend. She speaks five languages. — I have a friend who speaks five languages.
- He showed me the photo. He took it in Italy. — He showed me the photo that he took in Italy.
- We visited the museum. The museum has a famous painting. — We visited the museum which has a famous painting.
- That is the teacher. Her lessons are always interesting. — That is the teacher whose lessons are always interesting.
- London is the city. I grew up there. — London is the city where I grew up.
- The cake was delicious. My grandmother made it. — The cake that my grandmother made was delicious.
- Dr. Smith, ___ is a cardiologist, saved my father's life. — Dr. Smith, who is a cardiologist, saved my father's life. (non-defining)
Quick Reference
- Who = people (subject). Whom = people (object, formal). Which = things. That = people or things (defining clauses only).
- Whose = possession. Where = places. When = times.
- Defining clauses identify the noun and have no commas. Non-defining clauses add extra information and always have commas.
- Never use "that" in non-defining (comma) clauses.
- You can omit the relative pronoun when it is the object of a defining clause.
- Do not add an extra subject pronoun inside the relative clause.
Relative clauses are everywhere in English. The more you practice building them, the more natural and connected your sentences will sound. Pay attention to how native speakers and writers use them, and start incorporating them into your own speech and writing.
