Do You Need Commas Before Conjunctions?
The Blue Book of Grammar and Punctuation
Do You Need Commas Before Conjunctions?
A common debate in English grammar can concern whether commas need to be used before conjunctions such as and, or, and but.
These debates may stem from the fact that different people have been taught different guidelines about this punctuation. Style guides often differ about it as well.
Today’s post will help to clear things up so you’ll know whether and when to use commas before conjunctions in your writing.
The Basic Rule on Commas Before Conjunctions
If you’re looking for a general guideline, we recommend using a comma before coordinating conjunctions such as and, or, and but when they join two independent clauses. An independent clause is a group of words that include a subject and a verb and can stand alone as a complete thought.
Let’s look at a couple of independent clauses joined by a coordinating conjunction:
Jane is great at spelling, but her grammar needs some work.
First we will stop at the dry cleaner, and then we will go to the hardware store.
In each example, the clauses before and after the underlined conjunction are independent. A comma and a conjunction typically separate such clauses. Here’s another example:
I could go with you to the movies, or I could stay home and watch the game.
Once again we have two independent clauses that have a subject and verb and can stand alone as a separate sentence. We have combined them with the conjunction or preceded by a comma.
Possible Exceptions to the Comma Before a Conjunction
We’ve established that a general guideline is to include a comma before a coordinating conjunction joining two independent clauses.
In some cases, depending on style and preference, a writer might omit the comma from a sentence with two shorter independent clauses joined by a conjunction:
I’d rather walk but Jenna wants us to drive.
Tim ate pizza and Jon had fries.
In such sentences, including or omitting the comma is often more a matter of desired effect than of strict grammar. A writer might choose to keep the comma to create a pause:
I’d rather walk, but Jenna wants us to drive.
Tim ate pizza, and Jon had fries.
Some publications and style guides also may specify that writers should use as few commas as possible. Such guidance is becoming more prevalent, particularly as more people read content on mobile devices and the internet, where cumulatively less punctuation can result in swifter reading.
Get the Grammar Advice You Need
Looking for grammatical guidance for the usage of commas? Review our article on the Oxford comma. If you have thoughts or questions about the article on this page, you can leave us a note below.
If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.
Should there be a comma before “and” in a series? For example: He likes to eat candy, popcorn, suckers and ice cream?
Our post The Oxford Comma discusses what you need to know about the Oxford comma, its uses, and whether you need it.
Do you agree that if the second clause is dependent, ie is not a complete sentence on its own, one does NOT use a comma? I see this all the time and it makes me crazy. Ex: “Defendants continue to bulldoze through private and public lands and waters, and install transmission equipment and 17-story towers.” No comma, correct?
Your example doesn’t include a dependent clause; rather, it has a compound predicate.
Defendants [continue to bulldoze through private and public lands and waters] and [install transmission equipment and 17-story towers].
The same subject performs both actions.
No comma is necessary.
In a series of prepositional phrases joined by coordinating conjunctions, should commas be used before the coordinating conjunctions? For example: Did he find his shoes under the bed, or behind the door, or in the closet? Are the commas needed?
Your example sentence contains a series of three or more items; therefore, the commas are necessary (see Rule 1 of Commas). The first “or” is unnecessary.
Did he find his shoes under the bed, behind the door, or in the closet?
A sentence without a series of three or more items would be written without commas as follows:
Did he find his shoes under the bed or in the closet?
When did people start using commas before conjunctions? I was taught no commas in the 60s.
Teaching can differ among decades and U.S. locations. For our references, we consult resources on grammar ranging from the 1940s and 50s to the present day. As we do in the post, the majority of those resources advise to include a comma before a conjunction separating two independent clauses unless the clauses are short, in which case the punctuation can be a matter of writer style and preference.
Should a comma come after a coordinating conjunction in any situation?
Here are a couple of examples:
They went to the store at 7 p.m., but yes, they will be home in time.
They went to the store at 7 p.m., but, yes, they will be home in time.
They went to the store at 7 p.m., and unfortunately, they won’t be home on time.
They went to the store at 7 p.m., and, unfortunately, they won’t be home on time.
As the post states, we recommend using a comma before coordinating conjunctions, not after. Your sentences should be punctuated as follows:
They went to the store at 7 p.m., but yes, they will be home in time.
They went to the store at 7 p.m., and unfortunately, they won’t be home on time.
I have a question about the meaning of the following: Landlord may designate to Tenant either at the time of its Landlord’s approval, or, with respect to Permitted Improvements, at the expiration of the lease, those Improvements the Tenant must remove.
The correlative conjunction either/or with a comma after “or” are quite confusing. Can the Landlord designate which improvements, other than Permitted Improvements, to remove either at the time of its approval or at termination?
Your sentence looks as if it could be part of a legal document. Legal documents can have their own rules and possible interpretations. You may want to consult an attorney or a guide on writing in legal style.