Commas the Chicago Way: What’s Up With Independent Clauses and Commas?

 In Grammar

Or: Enter the grammar terms

Having dispensed with the easy stuff (Comma series #1) and everyone’s favorite series comma (Comma series #2) the Chicago Manual of Style is starting to really throw around those grammar terms, so we’re going to define them before we dive into the comma rules in this section.

If you are like me in that your explicit grammar instruction ended with elementary school, you might find that grammar terms can make language intimidating. I don’t want to scare you off. Read the definitions of the terms and refer back to them as needed.

(If you are like me in that you got to learn all this stuff officially when you were training to be a copyeditor, isn’t it nice to feel comfortable with the terms and be able to say something other than “it just sounds better that way”?)

A fun thing about grammar? There are multiple names for the same things. If the term is also called something else, I’ve put it in parentheses.

Independent clauses (main clauses)

Chicago tackles this in 5.225, for those of you playing along at home. They say that “an independent clause can stand alone as a sentence.” My favorite grammar site Grammar Bytes says that an independent clause “must contain a subject and a verb as well as express a complete thought.”


Beyoncé headlined Coachella in 2018.

Subject: Beyoncé
Verb: headlined
Complete thought? Yes!

Coordinating conjunctions

This is what Chicago 5.198 says. They “join words or groups of words of equal grammatical rank, such as two nouns, two verbs, two phrases, or two clauses.” If you are of a certain age, you might remember Schoolhouse Rock’s “Conjunction Junction” which focuses on three of the conjunctions saying “they’ll get you pretty far.” Their three: and, but, and or.

But there are actually seven coordinating conjunctions and they arrange themselves into my favorite grammar acronym: FANBOYS.

  • F = for
  • A = and
  • N = nor
  • B = but
  • O = or
  • Y = yet
  • S = so


If you didn’t attend Coachella in 2018 fear not, for you can watch Beyoncé’s headlining performance in the movie Homecoming: A Film by Beyoncé.


Merriam-Webster defines predicate as “the part of a sentence or clause that expresses what is said of the subject and that usually consists of a verb with or without objects, complements, or adverbial modifiers”

What that means:

  • There’s a subject.
  • The words that talk more about the subject make up the predicate.

In the example from the independent clauses section this would drill down to:

  • Subject: Beyoncé
  • Predicate: headlined Coachella in 2018.

You can see that the predicate lets us know more about the subject, Beyoncé

Compound predicates.

Sometimes there’s a lot going on in sentences and the predicate has more than one clause. When the two clauses share the subject that’s what’s known as a compound predicate.


Beyoncé danced and sang at Coachella.

This could have been two separate sentences:

  • Beyoncé danced at Coachella.
  • Beyoncé sang at Coachella.

But by combining the verbs into one sentence, you get a compound predicate. Bonus! You also have a smoother-reading sentence.

Imperative Sentences

In sixth grade, I was instructed in how to diagram sentences and it was a tearful, tearful time. Now, I’d probably find it soothing, but at that age the grammar terms were overwhelming. And no more so than with imperative sentences where the subject isn’t hanging out in the sentence.

Here’s what Chicago says in 5.122 about the imperative mood (which makes imperative sentences.) “The imperative mood expresses commands {go away!}, direct requests {bring the tray in here}, and, sometimes, permission {come in!}.”

What do you notice about all of those examples? They are missing their subject. Instead, the subject is you. Yes, you! You are the one who is supposed to go away, bring the tray in here, and come in.

The phrase that burbles from the dusty realms of my archived knowledge is “you, understood.” That’s what imperatives are all about. We understand that “you” are the subject of that sentence.

Now that we’ve got a handle on the definitions of those terms, let’s dive in.

Sand on the beach: Text: 6.22 Commas with independent clauses joined by coordinating conjunctions.

6.22 Commas with independent clauses joined by coordinating conjunctions

As with many things comma, the Chicago Manual of Style gives and then it takes away. It opens this section with the following: “When independent clauses are joined by and, but, or, so, yet, or any other coordinating conjunction, a comma usually precedes the conjunction.”

Pretty cut and dried, especially now that we’ve been reminded of what coordinating conjunctions are.


Do you want to watch a movie on Netflix, or should we go to the movie theater?

In that case, both parts of the sentence can stand on their own, so we know they are independent. The coordinating conjunction is or and Chicago instructs us to add that comma.

Now for the taking away. Directly after the above sentence, Chicago reminds us that things are never so cut and dried with the comma: “If the clauses are very short and closely connected, the comma may be omitted…unless the clauses are part of a series.”


Zoe wrote the film and Paul produced.

Because both sentences could stand on their own and they are closely joined, no comma is needed.

However, the “may” in “may be omitted” means that it’s not wrong to have a comma there. But because we are trending to a world of fewer commas you might as well leave it out.

Remember above when I jabbered on about imperative sentences? The knowledge you gained is going to help you with one more nuance of 6.22. They say: “These recommendations apply equally to imperative sentences…”

So! If you have an imperative sentence with a coordinating conjunction, there is a comma before that coordinating conjunction.


Buy a ticket for the matinee on Sunday, or go with Madelyn on Saturday.

And if your imperative sentence has independent clauses that are short and closely connected, no commas is needed.


Make up your mind and choose a movie.

Sand on the beach: Text: 6.23 Commas with compound predicates

6.23: Commas with compound predicates

Given that we’re trending to a world with fewer commas, it’s not surprising that Chicago says: “A comma is not normally used to separate a two-part compound predicate joined by a coordinating conjunction.”

You saw that usage with my example explaining compound predicates.


Beyoncé danced and sang at Coachella.

However, if the sentence structure will be confusing without the comma, Chicago does want you to put it in.


The soldier recognized the man who stole the milk, and yelled.

We need that comma in the sentence so people know that yelled is a compound predicate hooked up to the solider instead of an action connected to the thief.

Let’s talk about then as shorthand for and then. We see this shorthand a lot because no one wants a bunch of extra ands taking up room in the sentence when it’s accepted practice to just use then. However, if you are using this shorthand, Chicago says that you need to use a comma.


Will Smith was nominated for best actor in Ali, then for The Pursuit of Happyness.

Or, without the comma:

Will Smith was nominated for best actor in Ali and then for The Pursuit of Happyness.

Finally, if you have a compound predicate with three or more parts it follows the series comma rules.


Gina Prince-Bythewood wrote four episodes of A Different World, directed The Old Guard, and produced Daddy’s Girl.

That takes care of commas with independent clauses. Go forth into the independent clause world knowing that you know what you need to know about commas.

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A blue expanse of water. Text: Don't Let Headline-Style Capitalization Give You a Headache.Sand on the beach. Text: Commas the Chicago Way 6.24–6.26