Don’t Mix Them Up! Restrictive vs. Non-Restrictive Relative Clauses

Contents

In this article, we’ll look at the following points:

How relative pronouns are used in restrictive and non-restrictive structures
The meanings of these two structures
How they differ from each other

Quick Summary

Restrictive use refers to adding information that directly defines or identifies the preceding noun (or noun phrase). This is done by using a relative pronoun without commas.

By contrast, the non-restrictive use adds non-essential information to a sentence. In this case, the main focus of the sentence lies in the main clause, while the relative clause simply adds extra details. Removing the relative clause does not change the core meaning of the main clause.

Restrictive Use

The students who studied hard passed the exam.

Here, the relative clause “who studied hard” defines which students are being talked about. It tells us that only those who studied hard passed.
There may be other students who didn’t study hard, and they didn’t pass.

Non-Restrictive Use

The students, who studied hard, passed the exam.

In this sentence, “who studied hard” simply adds extra information. It means all the students studied hard, and they all passed the exam. Even if we remove the clause, the main message “The students passed the exam” still makes complete sense.

Relative Pronouns

Relative pronouns are grammatical words that add extra meaning to a preceding noun. The most common relative pronouns are “who,” “which,” and “that.” You’ve probably seen or used them in everyday English, so their basic usage should feel familiar to you.

However, one tricky aspect of relative pronouns is the difference between their restrictive and non-restrictive uses.

Restrictive use: adds essential information that directly identifies or defines the noun without separating it with commas. The main focus is to specify the noun.
Non-restrictive use: adds extra, non-essential information and is set off by commas.

Roughly speaking, the difference between these two uses can be seen in whether a comma is used with the relative pronoun. For example, consider the following two sentences:

I have a cat which is always hungry.

I have a cat, which is always hungry.

At first glance, they may look almost identical, but the presence or absence of the comma completely changes the meaning. Once you understand the difference between restrictive and non-restrictive uses, you’ll be able to see clearly how these two sentences differ.

Now, let’s take a closer look at how each form works in detail.

Restrictive Use

The restrictive use of a relative pronoun adds information that is essential to identify or define the noun before it. Because this information is necessary for the meaning of the sentence, the restrictive form is written without commas.

In English, using commas signals that the enclosed part is non-essential, while omitting commas indicates that the information is crucial to the sentence’s meaning.

Forming Restrictive Use of Relative Pronoun

A relative pronoun, especially “who” or “which,” is used without a comma in the following restrictive structure:

Noun (or noun phrase) + relative clause

The main purpose of this structure is to identify or define the noun that comes before it.

Again, when the restrictive use is applied, you’re directly adding information that helps identify the preceding noun. This idea is easier to understand when you look at a few example sentences, so let’s go over one that uses a restrictive relative clause.

I have a cat which is always hungry.

In this sentence, the relative pronoun “which” is attached to the noun “a cat,” directly describing its characteristic. Here, the relative clause “which is always hungry” restricts the meaning of “cat” to only the one that is always hungry.

Note that we don’t know how many cats the speaker actually has. It could be one or several. In either case, the focus of the sentence is on the specific cat that is always hungry.

That is my brother’s car which has a blue stripe.

The relative clause “which has a blue stripe” specifies which car we are referring to. In this sense, the relative pronoun is used in its restrictive form.

Since the restrictive use is applied, the main focus of the sentence is to identify my brother’s car. We don’t know whether he owns only one car or several cars, but this sentence refers specifically to the one with a blue stripe.

Non-Restrictive Use

When a relative pronoun is used in a non-restrictive way, the relative clause is set off by commas, showing that the enclosed information is non-essential. In this case, the parts outside the relative clause carry the main meaning of the sentence.

Forming Non-Restrictive Use of Relative Pronoun

A relative pronoun, especially “who” or “which,” is used with commas around the following relative clause:

Noun (or noun phrase) + comma + relative clause + comma

In a non-restrictive structure, the main clause contains the essential information, while the relative clause simply adds extra details.

The idea that “the main clause contains the essential information” can feel a bit abstract when explained only in words. So, let’s look at an example to see how a non-restrictive clause actually works.

I have a cat, which is always hungry.

In this sentence, the main clause is “I have a cat,” and the relative clause “which is always hungry” simply adds an extra detail about the cat.

The key point is that the main information “I have a cat” already stands complete on its own, implying that the speaker owns only one cat. The relative clause merely adds a bit more description: that this cat happens to be always hungry.

Direct Comparison: Restrictive vs. Non-restrictive

I have three daughters, who can play piano.

This sentence is non-restrictive. The main clause “I have three daughters” is already complete, so the sentence implies that the speaker has exactly three daughters. The relative clause “who can play the piano” simply adds extra information, telling us that all three of them can play.

Now, let’s see what happens if we remove the comma, changing it to the restrictive form:

I have three daughters who can play piano.

In this version, the meaning changes. The sentence now means that three of the speaker’s daughters can play the piano, implying that the speaker might have more than three children in total.

Here, the relative clause “who can play the piano” restricts the meaning of “daughters,” specifying which ones are being talked about.

About the Author: joe

Hi, I’m Joe. I completed my BA and MA at Purdue University. My research topic was effectiveness and reliability of standardized tests like the SAT and TOEFL. After that, I worked in the test development industry and designed questions to make sure they reflected the skills of interest. I’ve spent time on both the research side and the practical side of test design, and I want to support SAT learners here. Having seen how test questions are actually made, I can give students effective strategies for SAT test takers.