How do I know which relative pronoun to use?

Use who for people, which for things or animals, that for either (informal), where for places, and whose to show possession.

Why is "The man who he called me" wrong?

The relative pronoun replaces the subject, so adding another subject like "he" doubles it — the correct form is "The man who called me."

Do relative clauses always need commas?

No — defining clauses (essential to identify the noun) take no commas, while non-defining clauses (extra, removable info) take commas, as in "My brother, who lives in Ottawa, is visiting."

Grammar

Relative Clauses — Adding Detail

Use who, which, that, where to combine ideas into richer sentences — a key skill for moving from short, choppy writing to CLB 9+ complexity.

6 min read · Updated June 18, 2026 · By the Celpip.me editorial team · Free

Quick answer

Updated Sep 16, 2026

Relative clauses use who, which, that, where, and whose to combine two short sentences into one richer, complex sentence — for example, turning "I met a woman. She works at the embassy" into "I met a woman who works at the embassy." This skill directly boosts CLB 9+ Readability scores by replacing choppy writing with combined, sophisticated sentences.

How do I know which relative pronoun to use?: Use who for people, which for things or animals, that for either (informal), where for places, and whose to show possession.
Why is "The man who he called me" wrong?: The relative pronoun replaces the subject, so adding another subject like "he" doubles it — the correct form is "The man who called me."
Do relative clauses always need commas?: No — defining clauses (essential to identify the noun) take no commas, while non-defining clauses (extra, removable info) take commas, as in "My brother, who lives in Ottawa, is visiting."

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Key strategies

1.who = people, which = things, that = either, where = places, whose = possession.
2.Relative clauses let you combine two short sentences into one richer one.
3.Defining clauses (essential info) take no commas; non-defining clauses (extra info) take commas.
4.Do not repeat the subject: "The man who he called me" is wrong; "The man who called me" is correct.

What they do

A relative clause adds information about a noun, letting you combine ideas:

Two sentences: "I met a woman. She works at the embassy." One sentence: "I met a woman who works at the embassy."

Choosing the right word

who — people: "the teacher who helped me."
which — things/animals: "the book which won the prize."
that — people or things (informal): "the car that broke down."
where — places: "the city where I grew up."
whose — possession: "the man whose car was towed."

Do not double the subject

The relative pronoun replaces the subject — do not add another:

✓ "The man who called me was polite." ✗ "The man who he called me was polite."

Commas change the meaning

Defining (no commas) — essential to identify the noun: "The students who studied passed." (only those students)
Non-defining (commas) — extra, removable info: "My brother, who lives in Ottawa, is visiting."

CELPIP application

Short, simple sentences cap your score. Relative clauses are one of the easiest ways to write complex sentences — exactly what Readability at CLB 9+ rewards: "The proposal, which the council approved last week, will create new jobs."

Check yourself

A quick self-check on this lesson — pick an answer, then see the explanation. Not graded.

1. Choose the correct word: "That is the woman ___ won the award."

2. Combine correctly:

3. Places use which word? "This is the town ___ I was born."

4. Which sentence gives EXTRA (non-essential) information?

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