Non-Defining Relative Clauses

B1 · IntermediateRelative Clauses

My sister, who studies medicine, called me. Commas — this is extra information, not needed to identify her.

What you'll learn

  • A non-defining relative clause adds extra information that isn't needed to identify the noun
  • Non-defining relative clauses are always set off with commas
  • 'That' can never be used in a non-defining relative clause — only who/which/whose
  • The relative pronoun can never be omitted in a non-defining clause

Extra information, always with commas

A non-defining (or non-restrictive) relative clause adds extra detail about someone or something that is already clearly identified. Removing it wouldn't cause any confusion about who or what is meant — it just removes an extra fact. Because this information is 'extra,' it's always separated by commas.

"My sister, who studies medicine, called me."
"Mount Everest, which is the tallest mountain, is in Nepal."

The noun is already clear

Non-defining clauses typically follow proper nouns (names, places) or nouns that are already unique in context — like 'my brother' when you only have one. You don't need the clause to know who or what is meant; it's simply adding more information.

"Paris, which is the capital of France, attracts millions of tourists."
"My brother, who lives in Canada, is a doctor."

Never 'that,' never omitted

Two strict rules distinguish non-defining clauses from defining ones: the pronoun 'that' is never used, and the pronoun can never be dropped — it must always be there, along with its commas.

"This museum, which opened last year, is already famous."
"Our teacher, who has taught here for 20 years, is retiring."

Real English

"The Amazon River, which is the second longest river in the world, is in South America."
"My father, who grew up in Kyiv, now lives in Lviv."
"The Eiffel Tower, which was built in 1889, is in Paris."
"My manager, who is from Spain, speaks four languages."

Watch out

✗My sister, that studies medicine, called me.
✓My sister, who studies medicine, called me.

'That' can never be used in a non-defining relative clause — use who, which, or whose instead.

✗Mount Everest which is the tallest mountain is in Nepal.
✓Mount Everest, which is the tallest mountain, is in Nepal.

Non-defining relative clauses always need commas around them, since the information is extra, not essential.

✗My father, grew up in Kyiv, now lives in Lviv.
✓My father, who grew up in Kyiv, now lives in Lviv.

Unlike some defining relative clauses, the relative pronoun in a non-defining clause can never be omitted.

Real life — Sharing extra details

"Did you meet my colleague, who just moved here from Berlin?"

"Not yet! Is he the one working on the new project?"

"Yes, that's him. He used to work in Warsaw, which is where I met him."

"Interesting — I should introduce myself."

Practice

Exercise 1 · Choose the correctly punctuated sentence

Choose the correctly punctuated sentence.

Exercise 2 · Choose the sentence with extra, non-essential information

Choose the sentence where the clause adds EXTRA, non-essential information (I only have one car).

Exercise 3 · Choose the correct relative pronoun

Choose the correct relative pronoun for this non-defining clause: 'Mount Everest, ___ is the tallest mountain, is in Nepal.'

Exercise 4 · Choose the correct sentence

Choose the correct sentence.

Exercise 5 · Choose the correctly punctuated sentence

Choose the correctly punctuated sentence about a person's only brother.

Exercise 6 · Answer the question about pronoun omission

Can you omit the relative pronoun in a non-defining clause?

Exercise 7 · Choose the correct sentence

Choose the correct sentence.

Exercise 8 · Choose the correctly punctuated sentence

Choose the correctly punctuated sentence.

Exercise 9 · Combine the sentences

Combine into one sentence with a non-defining relative clause: 'The Amazon River is in South America. It is the second longest river in the world.'

Exercise 10 · Combine the sentences

Combine into one sentence with a non-defining relative clause: 'My father grew up in Kyiv. He now lives in Lviv.'

Exercise 11 · Sort into groups

The man that answered the phone was rude.
My father, who grew up in Kyiv, now lives in Lviv.
Students who arrive late must wait outside.
Mount Everest, which is the tallest mountain, is in Nepal.

0 / 4 sorted

Quick challenge

Five quick questions to check what stuck.

Question 1 / 5

Score: 0/0

Choose the correctly punctuated sentence.

You learned

  • A non-defining relative clause adds extra information that isn't needed to identify the noun.
  • Non-defining relative clauses are always set off with commas.
  • 'That' can never be used — only who/which/whose.
  • The relative pronoun can never be omitted in a non-defining clause.

Related grammar lessons

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