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Comma before “who”: The Definitive Guide

Comma before “who”: The Definitive Guide

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Ask anyone who’s ever written an essay how he or she feels about commas and you’re likely to receive a groan for an answer.

Despite the comma hate, this piece of punctuation has only a few basic rules.

Part of the problem is that writers tend to hyper-focus on how commas interact with specific words.

If, instead, you take a look at the function of that word in the context of the sentence containing it, you will be able to quickly and painlessly answer any comma question.

Additionally, there’s often an easy shortcut you can use to figure out commas before some words. “Who,” which is a relative pronoun, is one such word.

Let’s take a look at this word and determine when it requires a comma.


Do you ever need a comma before “who”?

Who is a relative pronoun, meaning that it is used most often to clarify something earlier in the sentence or to show the “relation” of the clause that follows it.

Whether you need a comma will depend on whether the clause after “who” is restrictive or whether it contains additional information that isn’t essential to the sentence.

If you have a restrictive clause, which is a clause that changes the meaning of your sentence when it is removed, you should not put a comma before “who.”

On the other hand, if the clause after “who” only provides some additional, unnecessary information you should add a comma.

Clauses and restrictive clauses

Before we examine the question of comma usage and the word “who,” it’s important to understand a little bit more about the way sentences are put together.

Put simply, a clause is the core building block of a sentence. At a minimum, it needs to include a verb; in most cases, it also includes a subject and an object, as well.

To be grammatical, a sentence needs to include one main clause. Most sentences also include subordinate clauses that add further information about the main clause, or change our understanding of it in some way.

You can usually tell whether you’re looking at the main or subordinate clause of a sentence by checking to see which contains the most important information.

Key to understanding when to use a comma before “who” is knowing that some subordinate clauses can be restrictive.

This means that they give the reader essential information about the main clause and that they cannot be removed without changing the sentence’s meaning.

Comma rules and restrictive “who”

“Who” is commonly used at the beginning of a clause that provides essential information about the topic of a sentence. As noted above, this means you are dealing with a restrictive clause.

Once you know your relative clause is restrictive, the question of whether to use a comma before “who” is an easy one.

Because restrictive clauses provide essential information, you should never add a comma in front of them.

That means that if you can’t take the clause beginning with “who” out of your sentence without changing its meaning, you should not add a comma before it.



“Lakshmi preferred the James Bond actor who spoke with an English accent.”co

“Of the three contestants, the one who took the biggest risks was the most interesting.”


In both of these examples, our “who” clause tells us key information about the topic of the sentence. That means we should not add a comma.

To check, let’s remove the clause from the first sentence: “Lakshmi preferred the James Bond actor.”

As you can see, the meaning of this sentence has now been completely changed, almost to the point where the sentence is meaningless.

In the original, the clause “who spoke with an English accent” let the reader know which of the various James Bond actors she preferred. With the clause removed, we have no way of knowing which actor she preferred, or what she preferred him over.

Using a comma before “who” for additional information

If “who” is not acting as a restrictive clause, the most likely use of it in a sentence is to provide additional information.

Because clauses that aren’t restrictive are basically optional, commas are used to provide a visual cue to the reader that he or she can skip what follows.

Again, the easiest way to tell the difference is to try and remove the clause with “who” from your sentence. If you find that everything still makes sense, you are dealing with a non-essential clause and should place a comma before “who.”

Keep in mind as well that if your non-essential clause appears in the middle of a sentence rather than at the end, you will need to follow the clause with a comma as well as put a comma at its start.



“After searching all morning I found the cat, who was sitting on the bed licking himself as though nothing was wrong.”

“Judy, who hated musicals, declined to accompany me to the screening of Les Misérables.”


In both of these sentences, the relative clauses beginning with “who” provide additional information about the topic of the sentence.

In the first, the relative clause describes what the cat was doing when the speaker found him. In the second, it gives us the likely reason that Judy did not want to go and see a musical.

Although knowing these facts add flavor to the sentence, they don’t change the basic meaning when removed.

That means we need to set them off with a comma before “who,” or, in the case of the second example, that we need to surround the relative clause with commas.

Grammar puzzler: who or whom?

As if commas aren’t confusing enough, the word “who” brings with it an extra chance for slip-ups. In a formal setting, you might sometimes see its old-fashioned cousin, “whom.”

Some people mistakenly think that “who” should always be “whom” when it appears towards the end of a sentence, but this is a misunderstanding.

Overcorrection to “whom” is a common problem in formal writing, so how do you tell which of these two words to use?

The key is to realize that you only use “whom” as the object of a verb. With that fact, everything falls into place.



“I gave the car to the valet, who parked it for me.”

“To whom did you give the car?”


In the first example, the word “who” is actually the subject of the clause “who parked it for me.” This means that even though it appears towards the end of a sentence you shouldn’t use “whom.”

In the second, even though “whom” is the sentence’s second word, it’s technically the indirect object of the verb “give.” That means you need “whom” instead of “who.”