Understanding Relative Clauses Pt. 1 (Who, Which, That)

Grammar Explanations

TL;DR - Key Takeaways Quick overview before you read
  • Relative clauses give extra information about nouns and start with relative pronouns like who, which, or that
  • Use "who" for people, "which" for things and animals, and "that" for either people or things (more informal)
  • "That" is less formal than "who" or "which" but very common in everyday spoken English
  • Don't use "what" as a relative pronoun - use "that" instead, and avoid double subjects like "the man who he lives"

⏭️ Already know who, which and that? Go straight to the mini-quiz!

Ready to level up? Continue to 👉 Part 2: Defining vs. Non-Defining Clauses & When to Omit Pronouns

What Are Relative Clauses?

Relative clauses give extra information about a noun. They start with relative pronouns (who, which, that, whose, where, when) and help us describe things more specifically.

Without relative clause: I met a woman. With relative clause: I met a woman who speaks five languages.

The relative clause "who speaks five languages" gives us more information about "a woman."

Relative Pronouns — Quick Overview

Different relative pronouns are used for different things:

  • who = people
  • which = things, animals
  • that = people or things (informal)
  • whose = possession (people or things)
  • where = places
  • when = times

In this part we'll focus on the three you'll use most: who, which, and that. We cover whose, where and when in Part 2.

WHO — For People

Use "who" when talking about people.

Examples

  • The woman who lives next door is a doctor.
  • I know someone who speaks Spanish.
  • The man who called you is waiting outside.
  • Students who work hard usually succeed.

Who can be the subject or object of the relative clause:

Subject (who does the action):

  • The girl who broke the window ran away. (she broke it)

Object (who receives the action):

  • The girl who I met yesterday is very nice. (I met her)
  • The people who we invited didn't come. (we invited them)

WHICH — For Things and Animals

Use "which" when talking about things or animals.

Examples

  • The book which is on the table is mine.
  • I bought a car which has low fuel consumption.
  • The dog which bit me was very aggressive.
  • The movie which we watched was excellent.

Which can also be the subject or object:

  • Subject: The car which crashed was going too fast.
  • Object: The car which I bought is red. (I bought it)

THAT — For People or Things

"That" can replace "who" or "which" in many cases. It's more informal and very common in spoken English.

Examples

For people (instead of "who"):

  • The woman that lives next door is a doctor.
  • I know someone that speaks Spanish.

For things (instead of "which"):

  • The book that is on the table is mine.
  • The car that I bought is red.

Important: "That" is less formal than "who/which" but very common in everyday English. Note that "that" cannot be used in non-defining (comma) clauses — more on that in Part 2!

Quick Reference: who, which, that

PronounUse forFormal?Example
whoPeopleYesThe woman who lives here...
whichThings / animalsYesThe book which is on the table...
thatPeople or thingsInformalThe car that I bought...

Common Mistakes with who, which, that

❌ Mistake 1: Wrong relative pronoun

  • ❌ The woman which I met was nice. (people = who/that)
  • ✅ The woman who I met was nice.

❌ Mistake 2: Using "what" instead of "that"

  • ❌ The book what I read was good.
  • ✅ The book that I read was good.

❌ Mistake 3: Double subject

  • ❌ The man who he lives next door is friendly.
  • ✅ The man who lives next door is friendly. (remove "he")

Practice

Choose who, which, or that:

  1. The woman _______ lives next door is a teacher.
  2. The book _______ I bought is on the table.
  3. The people _______ we met were very friendly.
  4. The car _______ crashed was going too fast.

Combine the sentences using a relative clause:

  1. I met a woman. She speaks five languages. → I met a woman _______.
  2. The car is mine. You saw it yesterday. → The car _______ is mine.

Correct the mistakes:

  1. The woman which I met was nice.
  2. The book what I read was good.
  3. The man who he lives next door is friendly.

Answers

  1. who / that
  2. which / that
  3. who / that (or omit — see Part 2!)
  4. which / that
  5. who speaks five languages
  6. which / that you saw yesterday
  7. The woman who I met was nice.
  8. The book that I read was good.
  9. The man who lives next door is friendly.

🎯 Take the Part 1 mini-quiz! (coming soon)

Ready for more? 👉 Part 2: Defining vs. Non-Defining Clauses & When to Omit Pronouns

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