Commas the Chicago Way: Commas with Relative Clauses, Appositives, and Descriptive Phrases

 In Grammar

Or: Different Terms, Same Structure

First come the grammar terms! Reading about The Chicago Manual of Style’s rules makes more sense if you know what a bunch of grammar terms mean. We tackle those first. If you are good with grammar, skip down to the end of the post to get to the comma talk.


Hey! It’s a Mad Libs–level grammar term! I know from hours of funny word enjoyment that a noun is a person place or thing. Chicago defines nouns in 5.4 saying “A noun is a word that names something, whether abstract (intangible) or concrete (tangible).” Chicago also talks about common and proper nouns, as well as count nouns and mass nouns.


Good old 5.225 in Chicago is where we find our definition of the clause. To have a clause you need to have a subject and a verb and anything else the verb needs. Clauses come in the independent (can stand alone) and dependent (cannot stand alone) variety.


Suzanne Collins wrote The Hunger Games.

  • Subject: Suzanne Collins
  • Verb: wrote
  • Other stuff: The Hunger Games

In this example, this sentence is an independent clause. As an independent clause it could be part of a sentence (Suzanne Collins wrote The Hunger Games to show how poverty and other factors affect children.) But it’s also just fine on its own.

Dependent clause (subordinate clause)

The term subordinate clause is going to appear below, so let’s spend a little time with the dependent/subordinate clause.

As stated above, dependent clauses cannot stand alone. They depend on another part of the sentence in order to make sense. Looking at our example sentence from above:

Suzanne Collins wrote The Hunger Games to show how poverty and other factors affect children.

Looking at just the dependent clause we get:

To show how poverty and other factors affect children.

If you came across that clause on its own, you would have no idea what’s going on with this sentence. Who or what is showing us about poverty and children? Without knowing what the independent clause says, you would be adrift. Chicago says, “Because a dependent clause is always subordinate to an independent clause for contextual meaning, it is also called a subordinate clause.”

Also note that there are three types of dependent clauses: content (noun) clauses; relative (adjectival) clauses; adverbial clauses. One of them will become important momentarily.

Relative pronoun

These are the pronouns that are like a good host at a party. According to Chicago 5.56 “A relative pronoun is one that introduces a dependent (or relative) clause and relates it to the independent clause.”

You can imagine a relative pronoun saying, “Dependent Clause, meet Independent Clause, you both like to talk about Suzanne Collins’s Hunger Games series.”

I bet you are wondering what words hang out in the quiver of relative pronouns. The ones in common use are who, which, what and that. It’s really important to match up each relative pronoun with the right thing.

Who is what you match with human beings: Who is Katniss Everdeen?
You wouldn’t say “Who is that hat?”

Which is the relative pronoun that matches up with animals or things: Which dog should get the extra treat? Which District had the best advantage in the Hunger Games?

What is matched with things that aren’t alive: What doormat did you choose at the store?

And finally, that is a word used for everything, human, animal, and things: That girl climbed a tree to hide. That Mockingjay symbol was adopted by the rebellion. That cornucopia held a lot of things contestants needed for survival.

Relative clause (defining clause)

Remember the relative pronoun we just finished talking about? We talked about it because relative pronouns are what introduce relative clauses. They are like the big neon sign pointing to the relative clause!


The girl who was on fire.

Remembering that those relative pronouns are the big neon signs that point to relative clauses, we know that who was on fire is the relative clause. We can also tell it’s a dependent clause because if we came upon just that clause, we would have a lot of questions.

There are other things to know about relative clauses according to Chicago 5.226. They are subordinate clauses, the ones that can’t stand alone. There are also some versions of relative clauses where the pronoun is implied. These are called contact clauses.

Fun fact about contact clauses? They often involve whiz-deletions and I’m going to leave it to you to research that term.

Nonrestrictive clause (nondefining clause, parenthetical clause)

Of the three names for the nonrestrictive clause, my favorite is parenthetical clause. That’s because nonrestrictive clauses are the parts that can be taken out and the sentence still makes sense. People who overuse parentheses use them to bracket nonrestrictive clauses.


Katness Everdeen, whose father died when she was eleven, often hunted with her friend Gale to help feed her family.

You can see that if we remove the nonrestrictive clause whose father died when she was eleven the sentence still makes sense:

Katness Everdeen often hunted with her friend Gale to help feed her family.

Nonrestrictive clauses are easy-peasy to find, what with those commas setting them off.


Appositive is one of those terms that sounds übergrammar to me. How about you? Let’s figure out what this thing is.

Chicago defines an appositive as, “a noun element that immediately follows another noun element in order to define or further identify it.” (5.23)


Peeta Mellark, son of the baker, was also chosen in District Twelve’s Reaping.

In this case, son of the baker meets the qualifications of a noun element and this noun element also comes right after the proper noun Peeta Mellark, another noun element, so we have our appositive.

Also note that we could have the appositive begin the sentence:

The son of the baker Peeta Mellark was also chosen in District Twelve’s Reaping.

Restrictive appositive (essential appositive)

Good old appositives come in restrictive and nonrestrictive varieties. I was going to find some sort of underwear connection (Boxers or briefs? Bras or jiggle?) but decided to discard that particular path of examples. Let’s dive in, starting with the restrictive, so we can feel our bodies relax when we get to the less-restrictive type.

Restrictive appositives need to be there, or we lose site of the meaning of the sentence. Let’s look at our previous example:

The son of the baker Peeta Mellark was also chosen in District Twelve’s Reaping.

In this case, the baker has three sons and we need to know which one was chosen.

Nonrestrictive appositive (nonessential appositive)

Now that we know what’s up with restrictive appositives, you can guess what nonrestrictive appositives are, right? If you can take the appositive out of the sentence and the sentence still makes sense, you’ve got yourself a nonrestrictive appositive.

Heading back to a previous example:

Peeta Mellark, son of the baker, was also chosen in District Twelve’s Reaping.

Since we can take out the noun element son of the baker and the sentence still makes sense, we’ve got ourselves a nonrestrictive appositive.

Descriptive phrase

Guess what doesn’t have a definition of a descriptive phrase. Did you guess The Chicago Manual of Style? Correct. Also my favorite website Grammar Bytes has failed me too. I found a good definition on a 2012-era Google Site created by an instructor at Trocaire College. That very old website says: “A Descriptive Phrase is a group of nouns, adjectives, or a verb, that act together to describe a single noun (person, place, thing, or quality).”


Effie Trinket, the escort of the District Twelve tributes, always put a bright face on things.

You can see the pattern forming. We can remove the escort of the District Twelve tributes and still have ourselves a sentence that makes sense:

Effie Trinket always puts a bright face on things.

Leaving the descriptive phrase in gives us more information about Effie Trinket.

Nonrestrictive phrase (nonessential phrase)

Much like our appositives above, this type of phrase is not necessary to understand what the sentence is talking about. Our sentence about Effie uses a nonrestrictive phrase which we can identify because it’s surrounded by commas.

Effie Trinket, the escort of the District Twelve tributes, always puts a bright face on things.

Having made it through the grammar terms we can now look at our comma rules!

6.27 Commas with relative clauses—“that” versus “which”

So! If you’ve spent any time in the grammar trenches, you know there’s something up about choosing between the words that and which.

If you’ve not spent time in those grammar trenches, trust me, it’s a thing. Chicago 6.27 is where we find out why one of those two words is chosen over the other.

Of note: both that and which lead a parade of pronouns: that/who/whom/whose; which/who/whom/whose.

Here’s the secret: that matches up with restrictive clauses and which matches up with nonrestrictive clauses.

Quick review: a restrictive clause is the clause that we need because without it we wouldn’t understand the sentence. A nonrestrictive clause is one that we could remove and still have an understandable sentence.

One more thing we need to know. What’s up with the commas?

Here’s the comma secret: restrictive clauses never have commas and nonrestrictive clauses are set off by commas.

Let’s look at some examples.

Restrictive clause:

The arrow that Katness shot at the Gamemakers got their attention.

Our restrictive clause is that Katness shot at the Gamemakers and the sentence would be too vague without it: The arrow got their attention. Because the clause is necessary it is a restrictive clause and is matched with that rather than which.

Nonrestrictive clause:

Katness’s arrow, which pierced an apple in the mouth of a roasted pig, got the Gamemakers attention.

Here you can see we still have a meaningful sentence even without which pierced an apple in the mouth of a roasted pig. That tells us we’ve got a nonrestrictive clause and should choose which instead of that.

Guess what! It’s not always true. Here’s the traditional Chicago walk back: “Although which can be substituted for that in a restrictive clause (a common practice in British English), many writers preserve the distinction between restrictive that (with no commas) and nonrestrictive which (with commas).”

Translation: When not editing British English, you could swap that and which, but if you run into a writer who likes the distinction, you’d better follow the rules.

6.28 Commas with appositives

The good news is that appositives follow the same pattern we’ve been encountering all along. Is the appositive restrictive? No commas. Is it nonrestrictive? Commas.

Example of restrictive, no commas:

The District 12 victor Haymitch Abernethy accompanied Katness and Peeta to Panem

Because there was one other District 12 victor, we need to specify that it was Haymitch Abernethy who accompanied Katness and Peeta. Because we need to be specific we have a restrictive appositive and thus no commas.

Example of nonrestrictive, commas:

Haymitch Abernathy, winner of the 50th Hunger Games, accompanied Katness and Peeta to Panem.

Because the sentence makes sense without winner of the 50th Hunger Games we know that the appositive is nonrestrictive and thus, we use commas.

Chicago notes that while restrictive appositives can use the possessive, it’s better to “avoid such a construction with a nonrestrictive appositive. Instead, reword as needed.”

Not: Katness’s sister’s cat’s bed.
Instead: The cat bed belonging to Katness’s sister.

6.29 Commas with descriptive phrases

And we continue the trend with descriptive phrases. Is your descriptive phrase restrictive (that is, essential to the sentence)? No commas. If it’s a nonrestrictive descriptive phrase, it does get commas.

Example of restrictive, no commas:

The tribute with skills in archery was not favored to win the 74th Hunger Games

Example of nonrestrictive, commas:

Peeta Mellark, with his camouflage skills, was the son of a baker and not favored to win the 74th Hunger Games.

And so we see that once we muddle through the vocabulary of this section the rules are the same throughout. Whether you have a relative clause, an appositive, or a descriptive phrase, being able to identify if your element is restrictive or nonrestrictive will guide you to the correct use of that or which and inform you if commas belong in your sentence.

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Sand on the beach. Text: Commas the Chicago Way 6.24–6.26