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Commas Before Relative Pronouns: The Definitive Guide

Commas Before Relative Pronouns: The Definitive Guide

“I know what pronouns are, but I’m kinda confused about the idea behind relative pronouns and I have no clue on how to punctuate sentences containing relative pronouns. 

If that’s totally you, you’ve certainly come to the right place. 

But don’t worry, Linguaholic got you covered!

You’re welcome. You can thank me later for writing this article up.



Is a comma always necessary before a relative pronoun?

In essence, commas are not always essentially placed before relative pronouns. The decision on whether to put a comma or not lies behind the degree of importance of the idea that the relative pronoun introduces. A comma is unnecessary when the relative pronoun introduces what we call a restrictive clause, whose meaning is utterly essential to the rest of the sentence. However, the comma has to be dropped when the clause only introduces an additional, removable idea known as a nonrestrictive clause.


What is a relative pronoun?

In a nutshell, a relative pronoun is a type of pronoun that introduces an adjective clause that aims to provide information about the subject.

Relative pronouns are simply your WH-words that are used not to ask questions, but rather to refer back to a mentioned noun instead.

The usage of the pronoun may change depending on whether the referred noun, also called an “antecedent,” is either a human or non-human entity.

For example, the relative pronoun “who” substitutes a person subject while “which” refers back to an inanimate object or an animal.

A relative pronoun’s role in sentence construction is to introduce an adjective clause that can be classified as either restrictive or nonrestrictive in terms of the degree of importance.

And, the decision of whether or not to insert a comma is dependent on the writer’s ability to distinguish a restrictive from a nonrestrictive clause.

A comma is unnecessary if the information introduced is highly significant to the meaning of the whole sentence.

Whereas, a comma needs to be placed before an idea that only aims to amplify or clarify the antecedent’s meaning, hence grammatically removable.

Let us now try to look at the differences between a restrictive or essential adjective clause and a nonrestrictive or inessential adjective clause.


The Restrictive or Essential Relative Clause

As mentioned, a restrictive clause carries some meaning that is highly essential with regards to the rest of the sentence.

This means that removing the clause would create sentential meaning that would be ambiguous, pragmatically unclear, or unpredictable.

The cardigan which Kurt Cobain wore during the 1993 MTV “Unplugged” performance was sold at a hefty amount of $334,000 in 2019.

The relative pronoun used in the above example is “which” which is used to refer back to the noun “cardigan.”

Now, to illustrate the pragmatic “emptiness” of the sentence without the restrictive relative clause, let’s look at the next example.

The cardigan was sold at a hefty amount of $334,000 in 2019.

Do you see any difference? What is it?

Obviously enough, the sentence still makes complete sense if we talk about grammaticality, doesn’t it?

However, it would leave any reader questioning which exact cardigan is being referred to unless the intended reader is an avid Nirvana fan.

Now, let’s try to compare the restrictive clause with the nonrestrictive one.


The Nonrestrictive or Nonessential  Relative Clause

As you may have already guessed, a nonrestrictive clause is simply information added to amplify or clarify the meaning of a noun.

We also refer to this clause as a parenthesis in stylistics, which is used for rhetorical or persuasive purposes.

This means that removing the entire relative clause along with the commas would still leave the meaning of the whole sentence intact.

Kurt Cobain’s unwashed, olive green, mohair cardigan, which he wore during the 1993 MTV “Unplugged” performance, was sold at a hefty amount of $334,000 in 2019.

Now, let’s try to remove the relative clause to see the difference.

Kurt Cobain’s unwashed, olive green, mohair cardigan was sold at a hefty amount of $334,000 in 2019.

Would you say that it would be possible to identify which exact cardigan is being referred to with the only information included?

If you answered “Yes, sure,” then it means you have already understood the gist of this post, which isn’t really that hard, apparently.

Also, I’m pretty sure that you didn’t miss noticing my usage of another nonrestrictive clause in the previous sentence.

At this point, I would like to assume that the confusion has been lessened in the least. 

If not, then feel free to tickle your brain cells a bit more by reading further.

To further exemplify the linguistic nuances behind relative pronouns, the next couple of sections provide more explanation and examples.


The Necessary Comma Before Relative Pronouns

To synthesize the ideas elaborated earlier, a comma before a relative pronoun is only necessary when it introduces “removable” information, not to mention the other essential comma at the end of the clause.

Apart from “which,” the other commonly-used relative pronouns are who and whom, wherein “whom” is used rather than “who” as the object of a verb or preposition.

That was a bit of a mouthful, I presume.

To put it simply, “whom” is generally used when the word after it is a noun or a pronoun instead of a verb.

Here are some examples for each.


Comma before the relative pronoun “who” example

Mr. Wilson, who is our grumpy 80-year old neighbor, often feeds our dog with pie or pizza.


Comma before the relative pronoun “whom” example

Clean-freak Lana, whom I share the apartment with, never fails to scold me for unwashed coffee cups.


When is a comma unnecessary before a relative pronoun?

Recognizing when not to place commas before relative pronouns is slightly trickier than the former one.

This is particularly true because there are more considerations to take before being able to make a decision, especially when writing isn’t necessarily a part of your daily routine.

Don’t fret though. This peculiarity doesn’t have to trip anyone up.

All these guiding principles become less taxing and more natural as linguistic competence advances.

Apart from the essentiality and non-removability aspects explained earlier, an additional “rule” to bear in mind is related to the pronoun “that.”

The reason is that the word “that” actually bears more functions than just being a relative pronoun, which is elaborated in ample detail here.

And now to recall when not to use a comma before your relative pronouns, here are a few more sentences.


Unnecessary comma before the relative pronoun “who” example

The waiter who has got some horrible neck and face tattoos is actually my younger brother.


Unnecessary comma before the relative pronoun “whom” example

The man whom I helped in crossing the street this morning said he’s been legally blind for only a year.


Unnecessary comma before the relative pronoun “that” example (instead of which)

The luggage that was recently found and returned by a good samaritan is mine.

One helpful note to remember is even though “that” could replace a person or a thing, it is still much better to use the appropriate pronoun to avoid misinterpretation.


What is an easy way to determine the difference between a restrictive and nonrestrictive clause?

Although I may have already explained things at length, there is an easy hack to determine whether or not to place a comma before a relative pronoun.

What we can do is simply look at how specific the antecedent is, which is, again, the noun being referred to by the relative pronoun.

(You already get the idea behind the word “relative,” right? That it is called this way because it “relates” to another word in the same sentence.)

Digression aside, we can try checking if the antecedent is specific enough or not.

If so, it would mean that a nonrestrictive clause subsequently follows.

Whereas, an unspecified antecedent would need restrictive information afterward.


An unspecified antecedent doesn’t need a pre-comma

The man whom I helped a while ago mentioned that he was homeless.


A specified antecedent needs a pre-comma

Mr. Joe Patterson, who mentioned that he was homeless, asked for some help from me a while ago.


In brief, we could also deduce that using a restrictive clause saves more space when compared to the nonrestrictive clause.


Frequently Asked Questions about commas & relative pronouns


What are some examples of relative pronouns?

The most commonly-used relative pronouns are “who,” “whom,” “which,” and “that”. They are used to introduce relative or adjective clauses that refer back to nouns or noun phrases called “antecedents.”


What is the difference between a restrictive and nonrestrictive clause?

A restrictive clause carries a meaning that is highly essential to the rest of the sentence, whereas a nonrestrictive clause only bears additional clarifying information to the noun being referred to.


What is an example of a restrictive relative clause?

“That little boy who is wearing a cucumber costume is my son.” In the sentence, “who is wearing a cucumber costume” is the restrictive relative clause. A restrictive clause doesn’t need to be encapsulated with commas.


What is an example of a nonrestrictive relative clause?

“That boy wearing a cucumber costume, who looks adorable, is my son.” In the sentence, “who looks adorable” is the nonrestrictive relative clause. A nonrestrictive clause necessitates a comma insertion before the relative pronoun.


When is a comma necessary and unnecessary before “which?”

A pre-comma is necessary before “which” when it introduces nonrestrictive or nonessential information. Whereas, a pre-comma is unnecessary when the clause introduced by “which” contains meaning that is highly important to the rest of the sentence.



To synthesize, relative or adjective clauses are introduced by relative pronouns including who, whom, which, and that.

Being able to determine whether an adjective clause is restrictive or nonrestrictive is the key behind the pre-relative pronoun comma insertion.

In a nutshell, these clauses are, and will always be, of utmost salience in constructing sentences that are non-obscure or unambiguous nonetheless.