How to Master Relative Clauses in English: The Complete 2025 Guide

Have you ever read a sentence and gotten lost in all the clauses and commas? Or maybe you're preparing for an English exam like IELTS and want to level up your grammar skills.

Either way, learning how to use relative clauses is an essential milestone on the journey to fluent, sophisticated English.

In this comprehensive guide, we’ll cover everything you need to know about relative clauses, including:

• What they are and how they work
• The different types and how to form them
• Common mistakes to avoid
• Tips and examples for using them in everyday speech and writing
• Why they're so important for exams like IELTS and academic English

And by the end, you'll have a blueprint for quickly improving your relative clause skills.

So let’s get started!

How to Master Relative Clauses in English: The Complete 2025 Guide

What Are Relative Clauses and How Do They Work?

A relative clause (also called an adjective clause or adjectival clause) is a type of dependent clause that modifies a noun.

It adds essential information about the noun and begins with a relative pronoun like who, which, that, whose, where or when.

For example:

• The book that I bought today is excellent.
• The scientist who invented the vaccine won a prestigious award.

In these sentences, the relative clauses (in bold) add crucial details about “the book” and “the scientist”.

A relative clause always follows the noun it modifies and is usually set off by commas in writing.

It makes your sentences more descriptive and interesting. Instead of writing:

• I read a book. The book was excellent.

You can combine them into one efficient sentence with a relative clause:

• I read a book that was excellent.

How Relative Pronouns Connect Clauses

Relative pronouns function as the subject or object of the relative clause.

• Who refers to people and is the subject of the clause.
  • The woman who lives next door is a doctor.
• Which refers to things and is the subject.
  • The house which stood on the hill was abandoned.
• That can refer to people or things and is the subject or object.
  • The music that she likes is jazz.
  • The cake that we ate was delicious.
• Whose shows possession or association.
  • The actor whose house we passed is famous.
• Where indicates place and refers to the object.
  • The restaurant where we ate dinner was lovely.
• When refers to time and is an object.
  • The year when she graduated was 2005.

Now let's look at the two main types of relative clauses.

What Are Relative Clauses and How Do They Work?

Types of Relative Clauses

There are two primary categories of relative clauses in English grammar:

1. Defining Relative Clauses

These provide essential information to identify the noun being modified. They tell which noun we are talking about.

For example:

• The book that I bought today is excellent.
• The scientist who invented the vaccine won an award.

Without the relative clause, we wouldn't know which specific book or scientist is being referred to.

Key notes:

• Defining relative clauses are not put in commas.
• You can sometimes omit the relative pronoun if it's not the subject of the clause (see examples below).

2. Non-Defining Relative Clauses

These simply add extra information and are not needed to identify the noun.

For example:

• My friend Julie, who lives in New York, is visiting this weekend.
• Mount Fuji, which is located in Japan, is an active volcano.

The non-defining clauses (in bold) just give us more details about “My friend Julie” and “Mount Fuji” but do not define them.

Key notes:

• Non-defining relative clauses are separated by commas.
• You cannot omit the relative pronoun.

Now let's look at some examples of how to form relative clauses in sentences.

Types of Relative Clauses

Forming Relative Clauses in English

When forming relative clauses, the main things to focus on are:

• Choosing the correct relative pronoun
• Using the appropriate punctuation (commas for non-defining clauses)
• Placing the clause directly after the noun it describes

Let's break it down with some examples:

Relative Clauses with 'Who'

Use 'who' to refer to a person as the subject of the clause:

• The man who lives next door is very friendly.
• My uncle who studied in Paris sent me a postcard.

Who can be the subject but not the object. For objects, use whom or that:

• The boy whom we met yesterday plays soccer.
• The woman that I saw was a famous actor.

Relative Clauses with 'Which'

Use 'which' when referring to inanimate things, animals, ideas, etc:

• The house which stood on the hill was abandoned.
• The book which I read last month was excellent.

We also use which to refer to entire clauses or sentences:

• He failed his driving test, which surprised no one.

Relative Clauses with 'That'

'That' can refer to people, things or entire clauses. It can function as the subject or object:

• The song that played on the radio was catchy.
• The man that wore a red shirt left early.

Note: In defining clauses, you can often omit 'that' as the object:

• The book Ø I read was exciting.

But if it is the subject, you cannot omit it:

• The person that called me was my sister.

Relative Clauses with 'Where' and 'When'

'Where' refers to a place and 'when' refers to a time as the object of the clause:

• This is the park where we played as children.
• March is the month when spring begins.

Non-Defining Relative Clauses

These always require commas:

• My brother, who graduated top of his class, just got hired at Google.

• The Taj Mahal, which was built in the 1600s, is an iconic Indian landmark.

Okay, now that we've covered the basics of forming relative clauses, let's go over some common mistakes to avoid.

Common Mistakes When Using Relative Clauses

Like any new grammar concept, relative clauses take practice to use correctly. Here are some of the most common mistakes to watch out for:

Using the Wrong Pronoun

Make sure to use “who” for people, “which” for things, and “that” when the pronoun can be either subject or object:

• The man who (not which) spoke to us was very friendly.
• The book which (not who) I borrowed from the library is excellent.
• The cake that we bought was delicious.

Misplacing or Omitting Commas

Non-defining clauses require commas, while defining clauses do not:

• The actor, who comes from Australia, starred in that movie we saw. (non-defining)

• The actor that starred in that movie we saw comes from Australia. (defining)

Unclear Reference

Make sure it’s clear which noun the relative clause refers back to:

• The stylist cut the hair of the actress who was starring in the movie. (unclear)

Better:

• The stylist cut the hair of the actress who was starring in the movie.
• The stylist cut the hair of the actress that was starring in the movie.

Overusing “Which”

Limit using “which” at the beginning of a relative clause, and try to use “that” instead, for a more natural reading flow.

Dangling Clauses

Make sure the relative clause clearly connects back to a specific noun in the main sentence:

• Dangling: The book was brilliantly written, which inspired me.

Better:

• The book, which was brilliantly written, inspired me.

Okay, now that we’ve got a handle on how to form relative clauses and some pitfalls to avoid, let’s look at why mastering relative clauses is so useful for everyday English.

The Importance of Relative Clauses in Everyday English

From texting a friend to writing an academic paper, being able to correctly use relative clauses enables you to:

Be More Precise and Descriptive

Relative clauses allow you to pack more descriptive details into a sentence:

• My friend Julie loves musicals. She lives in New York.

Better:

• My friend Julie, who lives in New York, loves musicals.

Combine Sentences Smoothly

You can use relative clauses to combine sentences and avoid repetition:

• I have a colleague. She works in public relations. She is from Scotland.

Combined:

• I have a colleague who works in public relations and is from Scotland.

Clarify Which Noun You Mean

Defining relative clauses identify which specific person or thing you are talking about:

• The book that I read was very insightful. (Which book?)

• The scientist who invented the vaccine won a prestigious award. (Which scientist?)

Add Supplementary Details

Non-defining relative clauses let you add interesting bonus facts without cluttering sentences:

• Mars, which is known as the Red Planet, is the fourth planet from the sun.

As you can see, precision is power when it comes to relative clauses!

Now let’s look at why they are absolutely vital for success on exams like IELTS and TOEFL.

Why Relative Clauses Are Essential for IELTS and Academic English

Many students aiming for top IELTS scores get stuck at band 6 or 6.5 in their writing. Why?

One major reason is not using complex sentences like those formed with relative clauses.

Let's look at some key reasons why relative clauses help boost your IELTS Writing and Speaking:

Demonstrate Grammatical Range

The IELTS grading criteria explicitly mention using a variety of complex structures. Using relative clauses shows the assessor you can go beyond simple sentences.

Increase Lexical Resource Score

In addition to grammar variety, lexical resource (your vocabulary and precision) accounts for 25% of your IELTS Writing score. Relative clauses allow you to packed more descriptive details into sentences.

Showcase Natural, Sophisticated Expression

The Speaking module assesses your ability to express ideas naturally. Relative clauses help you combine ideas smoothly and avoid unnatural repetition.

Achieve Clarity and Concision

Getting ideas across accurately in as few words as possible is key in IELTS Writing and Speaking. Relative clauses allow you to be more precise and concise.

Level Up Your Sentence Structures

IELTS essay graders look for a range of complex and simple sentence structures. Relative clauses help you add sophistication without making sentences overly long or confusing.

In summary, developing your relative clause skills is a must for getting to IELTS band 7 or higher.

Now let's go over some tips and practice strategies.

Why Relative Clauses Are Essential for IELTS and Academic English

Tips and Resources for Improving Your Relative Clause Skills

Like any new grammar concept, mastering relative clauses takes practice and exposure. Here are some tips:

Study Examples in Context

Read news articles, scientific journals, and literary writing that use relative clauses. Take note of how they are formed and used in natural contexts.

Combine Sentences Deliberately

Take two simple sentences and practice combining them into one sentence using a relative clause. Start with sentences on familiar topics.

Do Targeted Grammar Exercises

Sites like British Council LearnEnglish have great relative clause exercises for guided practice.

Get Feedback from Native Speakers

Ask an English teacher or language exchange partner to check examples of your relative clauses and provide feedback.

Reference Trusted Books and Websites

Consult grammar resources like Practical English Usage by Michael Swan or the Grammar Monster articles on relative clauses.

Study Real Examples in Books/Newspapers

When reading academic texts or news articles, highlight well-written relative clauses and take note of how they are formed.

Review IELTS/OET Prep Books

Many IELTS and OET exam preparation books have chapters dedicated to relative clauses with practice questions.

With a combination of studying reputable grammar resources, practicing deliberately, and getting feedback, your relative clause skills are sure to improve rapidly.

Conclusion: The Key to Sophisticated, Expressive English

In closing, being able to correctly form and use relative clauses—whether you're texting a friend or taking the IELTS—is an essential milestone in your English learning journey.

Relative clauses allow you to be more precise and descriptive, combine ideas smoothly, and demonstrate grammatical range and sophistication.

While they take practice to master, having a grasp of relative clauses can elevate your writing, speaking, and exam performance to the next level.

So start paying closer attention to relative clauses when you read or have conversations. Challenge yourself to combine two sentences using a relative clause. And leverage online resources for targeted practice.

With time and deliberate practice, you'll be able to use relative clauses fluidly to communicate complex ideas clearly and expressively in English.

Frequently Asked Questions

Here are some common relative clause questions:

Q: When can I omit the relative pronoun in a defining clause?

A: You can omit the relative pronoun when it is the object of the clause. For example:

• The book (that) I read yesterday was excellent.

But don't omit it when it is the subject:

• The man who called me was my brother.

Q: What’s the difference between “which” and “that”?

A: The main difference is that “which” is more common in non-defining relative clauses, while “that” is more common in defining relative clauses. However, some style guides now accept using “which” in defining clauses too.

When in doubt, choose “that” for defining and “which” for non-defining clauses.

Q: How do I practice relative clauses for IELTS Writing?

A: When practicing IELTS essays or letters, make an effort to include 1-2 relative clauses per paragraph. Get feedback from teachers on your accuracy. Also study sample essays that use relative clauses well.

With time, using relative clauses will become second nature in your IELTS Writing!