Non-Defining Relative Clauses: Adding Information with Precision
Grammar Rule in 30 Seconds
Non-defining relative clauses provide optional extra information about a noun and must be set off by commas.
- Always use commas to separate the clause from the main sentence.
- Never use 'that' as a relative pronoun in non-defining clauses.
- The sentence must remain grammatically complete if the clause is removed.
Non-defining relative clauses add extra information about a noun that is already clearly identified. They are separated by commas and never use that.
Defining (no commas)
The report that arrived today needs signing.
Which report? The one that arrived today.
Non-defining (commas)
The report, which arrived today, needs signing.
We already know which report — added info.
Sentence Relatives (which → whole idea)
When which refers to the entire preceding situation:
✅ She offered to cover the costs, which was incredibly generous.
✅ The project ran over budget, which disappointed the investors.
Quantifier + of whom / of which
✅ The delegates, most of whom had flown in from abroad, were exhausted.
✅ The proposals, several of which were innovative, were shortlisted.
✅ The applicants, none of whom met the criteria, were rejected.
Key Rule
❌ My colleague, that works in finance, → ✅ My colleague, who works in finance,
Never use that in a non-defining relative clause.
Relative Pronoun Usage
| Function | Pronoun | Example |
|---|---|---|
|
Person (Subject)
|
who
|
My friend, who is a doctor, is here.
|
|
Person (Object)
|
whom
|
The man, whom I met, is nice.
|
|
Thing (Subject/Object)
|
which
|
The book, which I read, is good.
|
|
Possession
|
whose
|
My neighbor, whose dog barks, is loud.
|
|
Place
|
where
|
Paris, where I live, is lovely.
|
|
Time
|
when
|
July, when it is hot, is my favorite.
|
Meanings
Non-defining relative clauses provide additional, non-essential information about a noun. They are parenthetical and require commas to indicate that the information is supplementary.
Supplementary Detail
Adding descriptive details that do not restrict the identity of the noun.
“The Eiffel Tower, which was built in 1889, is an iconic landmark.”
“My car, which I bought last year, is already having engine trouble.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Noun, pronoun + verb, ...
|
John, who is tall, is my brother.
|
|
Negative
|
Noun, pronoun + neg + verb, ...
|
John, who isn't tall, is my brother.
|
|
Object
|
Noun, pronoun + subject + verb, ...
|
John, whom I know, is my brother.
|
|
Possessive
|
Noun, whose + noun + verb, ...
|
John, whose car is red, is my brother.
|
|
Place
|
Noun, where + subject + verb, ...
|
Paris, where I live, is beautiful.
|
|
Time
|
Noun, when + subject + verb, ...
|
July, when it is hot, is great.
|
Formality Spectrum
Mr. Jones, who is a renowned scholar, will speak. (Academic lecture)
Mr. Jones, who is a scholar, will speak. (Academic lecture)
Mr. Jones, who's a smart guy, is speaking. (Academic lecture)
Mr. Jones, who's a total brain, is talking. (Academic lecture)
Relative Clause Types
Defining
- No commas Essential info
Non-Defining
- Commas Extra info
Defining vs Non-Defining
Examples by Level
My mom, who is a teacher, is nice.
This book, which is old, is good.
My dog, who is brown, runs fast.
Paris, which is big, is beautiful.
Mr. Smith, who lives next door, is kind.
The car, which is red, is fast.
My phone, which I lost, was new.
Sarah, who is my friend, is coming.
The Eiffel Tower, which was built in 1889, is famous.
My brother, who works in London, visits often.
The house, which has a big garden, is for sale.
My laptop, which I bought yesterday, is broken.
The CEO, who has led the firm for a decade, resigned.
This theory, which was proposed by Einstein, is complex.
My car, which is a vintage model, needs repairs.
The city, where I grew up, has changed a lot.
The candidate, whom we interviewed yesterday, is highly qualified.
The painting, which was stolen in 1990, was finally recovered.
My colleague, whose expertise is in AI, led the project.
The treaty, which was signed last month, is now in effect.
The author, whose latest novel has received critical acclaim, is touring.
The infrastructure, which had been neglected for decades, was finally renovated.
The experiment, which yielded unexpected results, was repeated.
My mentor, whom I have known for years, provided invaluable advice.
Easily Confused
Learners often forget the commas or use 'that' incorrectly.
Learners struggle with object pronouns in relative clauses.
Learners use 'that' for everything.
Common Mistakes
My mom that is nice is here.
My mom, who is nice, is here.
My friend who is tall is here.
My friend, who is tall, is here.
The book that I read, which is good, is here.
The book, which I read, is good.
My dog who is brown is fast.
My dog, who is brown, is fast.
The car that I bought, which is red, is fast.
The car, which I bought, is red.
Mr. Smith who lives here is nice.
Mr. Smith, who lives here, is nice.
My phone that I lost was new.
My phone, which I lost, was new.
The Eiffel Tower that was built in 1889 is famous.
The Eiffel Tower, which was built in 1889, is famous.
My brother who works in London visits.
My brother, who works in London, visits.
The house that has a garden is for sale.
The house, which has a garden, is for sale.
The candidate that we interviewed is qualified.
The candidate, whom we interviewed, is qualified.
The painting that was stolen is back.
The painting, which was stolen, is back.
My colleague that is an expert led it.
My colleague, who is an expert, led it.
The treaty that was signed is in effect.
The treaty, which was signed, is in effect.
Sentence Patterns
My ___, who is ___, is very ___.
The ___, which was ___, is now ___.
My colleague, whose ___ is ___, led the project.
The city, where ___, is famous for its ___.
Real World Usage
Our manager, who is on leave, will reply later.
My cat, who is a genius, just learned to open the door.
The suspect, who was arrested yesterday, denied the charges.
The museum, which houses ancient art, is a must-see.
My previous role, which involved leading a team, was rewarding.
The pizza, which is extra cheesy, is my favorite.
Check the commas
No 'that'
Test the clause
Formal tone
Smart Tips
Use non-defining clauses to add background info without cluttering the main point.
Use 'who' for people and 'which' for things.
Use non-defining clauses to combine two sentences into one.
Remember 'whose' works for both people and things.
Pronunciation
Pause
You must pause slightly at the commas.
Parenthetical
The noun ↗, the clause ↘, the rest ↗.
The clause is a drop in pitch.
Memorize It
Mnemonic
Commas are like a hug; they hold the extra info in place.
Visual Association
Imagine a sentence as a train. Defining clauses are the engine (essential). Non-defining clauses are a passenger car attached with commas—you can unhook it and the train still runs.
Rhyme
If the info is extra and you want to be clear, put commas around it and keep 'that' out of here.
Story
Imagine you are introducing your friend, Sarah. You say: 'Sarah, who loves pizza, is coming over.' If you remove 'who loves pizza', you still know exactly who is coming. The commas act like little fences keeping the extra detail separate.
Word Web
Challenge
Write 5 sentences about your family using non-defining relative clauses.
Cultural Notes
Often used in formal writing to add politeness.
Used frequently in journalism for background info.
Essential for precision in research papers.
Relative clauses evolved from Old English demonstrative pronouns.
Conversation Starters
Tell me about a city, which you have visited, that you loved.
Who is a person, whom you admire, that has influenced you?
Describe your favorite book, which you have read many times.
Talk about a place, where you grew up, that is special.
Journal Prompts
Common Mistakes
Test Yourself
My brother, ___ lives in London, is a pilot.
Which sentence is correct?
Find and fix the mistake:
The book, that I read, is good.
John is my friend. He lives in Paris.
You can use 'that' in a non-defining clause.
A: Who is Sarah? B: Sarah, ___ is my sister, is a doctor.
is / my / , / , / brother / who / tall / is
Match each item on the left with its pair on the right:
Score: /8
Practice Exercises
8 exercisesMy brother, ___ lives in London, is a pilot.
Which sentence is correct?
Find and fix the mistake:
The book, that I read, is good.
John is my friend. He lives in Paris.
You can use 'that' in a non-defining clause.
A: Who is Sarah? B: Sarah, ___ is my sister, is a doctor.
is / my / , / , / brother / who / tall / is
Match the pronoun to the noun.
Score: /8
FAQ (8)
No, never. 'That' is only for defining clauses.
Commas show that the information is extra and not essential.
Use a comma before the relative pronoun and a period at the end.
Yes, it is common in formal writing but also used in speech.
If you remove the clause and the sentence still makes sense, it's non-defining.
Yes, 'whom' is the object form of 'who' and is used in formal contexts.
Use 'whose' for possession, even for things.
Rarely, as it's too formal for quick messages.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Cláusulas de relativo explicativas
Spanish doesn't have the 'that' vs 'which' distinction.
Propositions relatives explicatives
French grammar is more rigid with pronoun selection.
Nicht-restriktive Relativsätze
German requires case agreement for the pronoun.
連体修飾節
Japanese uses particles instead of relative pronouns.
الجملة الموصولة
Arabic relative clauses often require a resumptive pronoun.
定语从句
Chinese structure is entirely pre-nominal.
Learning Path
Prerequisites
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