Defining Relative Clauses (who, which, that)

Level: B1. A defining relative clause points to exactly which person or thing you are talking about. It joins extra information onto a noun with a relative pronoun — who, which or that — so you can say the woman who lives next door instead of two short sentences. This lesson shows the three pronouns, when you can drop them, and why commas must stay away.

The rule

A clause is a group of words with its own verb. A relative clause is a clause that describes a noun and begins with a relative pronoun. A defining relative clause gives essential information: it answers “which one?” and you cannot remove it without losing the meaning. In The man who fixed my car is here, the clause who fixed my car tells you which man — drop it and nobody knows who is here.

Choose the pronoun by what the noun is:

• who for people: the student who studies hard;
• which for things and animals: the car which broke down;
• that for both people and things: the student that studies hard, the car that broke down.

In defining clauses that is very common and often preferred in speech, especially after words like everything, all, the only and superlatives (the best film that I’ve seen).

Two rules protect the meaning. First, no commas around a defining relative clause — it is part of the noun it describes, not an aside. Second, when the relative pronoun is the object of the clause (the verb already has its own subject), you can leave the pronoun out: the film (that) we saw last night, the person (who) I met. When the pronoun is the subject, you must keep it: the man who called (you cannot drop who here).

who, which, that — the pattern

Example sentences

Common mistakes

• ❌ The man, who called you, is my boss. → ✅ The man who called you is my boss. A defining clause takes no commas.
• ❌ The book what I read was good. → ✅ The book that I read was good. What is not a relative pronoun after a noun; use that/which.
• ❌ The car who broke down is mine. → ✅ The car which/that broke down is mine. Use which/that for things, who only for people.
• ❌ The man who he called you is my boss. → ✅ The man who called you is my boss. Do not add an extra subject pronoun after the relative pronoun.
• ❌ This is the house which Jack built it. → ✅ This is the house that Jack built. Do not repeat the object with it.
• ❌ The woman which lives next door. → ✅ The woman who/that lives next door. People take who or that, not which.

A short conversation

A: Is that the colleague who helped you with the report? B: No, that’s the one who sits near the window. The person that helped me is away today. A: And the laptop that you borrowed — is it his? B: Yes, it’s the laptop he lent me last week.

Usage notes

• Dropping the pronoun. Only an object pronoun can go, and only in a defining clause: the song (that) you played. You can never drop a subject pronoun: the song that won needs that.
• that vs which/who. In defining clauses that is fully acceptable for both people and things and is often the natural choice in speech. Some style guides prefer which/who in formal writing, but that is not an error here.
• whose and where. Use whose for possession (the author whose book won) and where for a place (the town where I grew up). When works the same way for time: the day when we met.
• Prepositions. In everyday English the preposition goes at the end: the house that I live in. The formal pattern the house in which I live uses which (never that) and keeps the pronoun.

Compared with…

• Non-defining relative clauses add extra, non-essential information and always take commas: My brother, who lives in Rome, is a chef. Remove that clause and you still know who you mean. They never use that, and you cannot drop the pronoun. See Non-Defining Relative Clauses (with commas).
• More advanced relative structures — relative clauses with prepositions, quantifiers (some of whom), and reduced clauses — build on this foundation. See Advanced Relative Clauses.

Quick recap before you practise.

Practice

Quiz

Recap cheat-sheet

Next

• Next topic: Non-Defining Relative Clauses (with commas)
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