Non-defining Relative Clauses
Non-defining relative clauses are English's elegant way of adding extra information about people, places, and things that are already clearly identified. Unlike defining relative clauses, these provide bonus information that could be removed without changing the essential meaning of the sentence. They're the sophisticated tool for adding descriptive detail whilst maintaining grammatical precision.
Marked by commas and using only who and which (never that), non-defining relative clauses create a more formal, literary tone that's essential in academic writing, journalism, and professional communication. They allow you to provide additional context, background information, or interesting details without creating separate sentences, resulting in more sophisticated and flowing prose.
What makes non-defining relative clauses particularly valuable is their ability to enhance your writing with descriptive richness whilst maintaining clarity. They let you paint fuller pictures of people and situations, provide context that helps readers understand backgrounds and relationships, and demonstrate advanced command of English grammar that elevates your communication style.
Mastering non-defining relative clauses will transform your English from basic communication to sophisticated expression. They're the hallmark of educated, formal writing and speaking, allowing you to provide nuanced information and create the kind of detailed, flowing sentences that characterise professional and academic discourse.
Formation
Structure
Main clause , relative pronoun + extra information , continuation
Commas separate the additional information from the main clause
Who (for people):
- My brother, who lives in Spain, is a teacher.
- Shakespeare, who wrote Hamlet, died in 1616.
- The Prime Minister, who was elected last year, visited today.
Which (for things):
- London, which is the capital, has 9 million people.
- The iPhone, which Apple launched in 2007, changed technology.
- My car, which I bought last month, is very reliable.
Key Differences from Defining Clauses
Non-defining (Extra Info):
My sister, who lives in Paris, is a doctor.
↳ I have only one sister
The Eiffel Tower, which was built in 1889, is famous.
↳ There's only one Eiffel Tower
Defining (Essential Info):
My sister who lives in Paris is a doctor.
↳ I have multiple sisters
Students who study hard succeed.
↳ Not all students, only those who study
Crucial Punctuation Rules
1. Always use commas:
Paris, which is the capital of France, is beautiful.
2. Never use 'that':
✅ London, which is expensive, attracts tourists.
❌ London, that is expensive, attracts tourists.
3. Cannot omit the relative pronoun:
✅ The book, which I read yesterday, was brilliant.
❌ The book, I read yesterday, was brilliant.
Common Mistakes to Avoid
❌ "My brother who lives in Spain is a teacher."
✅ "My brother, who lives in Spain, is a teacher."
Use commas when giving extra information about someone already identified
❌ "London, that is expensive, attracts tourists."
✅ "London, which is expensive, attracts tourists."
Never use 'that' in non-defining relative clauses - only 'who' and 'which'
❌ "The book, I read yesterday, was brilliant."
✅ "The book, which I read yesterday, was brilliant."
Cannot omit relative pronouns in non-defining clauses
❌ "Shakespeare, who he wrote Hamlet, died in 1616."
✅ "Shakespeare, who wrote Hamlet, died in 1616."
Don't repeat the subject with a pronoun after the relative pronoun
Pronunciation and Intonation
Non-defining clauses have different intonation:
- Lower pitch for the relative clause
- Slight pauses at the commas
- Return to normal pitch after the clause
Example intonation pattern:
My brother, (lower pitch) who lives in Spain, (normal pitch) is a teacher.
Defining vs Non-defining: When to Use Each
Use Defining When:
- You need to identify which one
- There are multiple possibilities
- The information is essential
- Removing it changes the meaning
"The students who study hard pass. (not all students)"
Use Non-defining When:
- The person/thing is already clear
- Adding bonus information
- The information is interesting but not essential
- Removing it doesn't change the core meaning
"The students, who are very dedicated, passed. (all students)"
Tips for Formal Writing
Academic writing:
Use non-defining clauses to add citations, dates, and scholarly context without disrupting flow.
Journalism:
Perfect for adding background information about people in news stories.
Business writing:
Useful for providing company information, job titles, and professional context.
Creative writing:
Creates sophisticated sentences and helps build character and setting descriptions.
Quick Reference Guide
Remember:
- Purpose: Add extra information about already identified nouns
- Commas: Always use commas to separate the clause
- Pronouns: Only 'who' (people) and 'which' (things) - never 'that'
- Removal test: The sentence must still make sense without the clause
- Cannot omit: Relative pronouns cannot be left out
- Intonation: Lower pitch and slight pauses at commas
- Formality: More formal and literary than defining clauses
- Position: Usually comes immediately after the noun, but can be at the end