The more you get right in your manuscript before submitting to editors, the less work they'll have to do on mechanical issues—and the more time they can spend on making your writing shine. Plus, learning the conventions of fiction style* can save you money.
*This is Articulate Editing house style, which is based on generally accepted fiction conventions (in the US) and a pinch of personal opinion. Most of what is written here will apply across the board. If a guideline has wiggle room, I'll let you know. And if you're working with a publisher, make sure you follow their specifications, as their house style may differ slightly. (This style guide also applies to creative nonfiction.)
Commas with ...
Commas are the trickiest punctuation mark. A few rules are firm, but many can be bent—especially in creative writing—in service to the writer's intent and ear. While it's an oversimplification to "put a comma wherever you hear a pause," listening to the rhythm of your prose is important. Too many commas, even grammatically correct ones, can make your writing choppy, and too few can hinder clarity.
When it comes to punctuation, there’s a difference between formal prose and creative writing. Readers rely on formal prose for information; the purpose of every comma and dash should be clear and unambiguous. In creative writing, emotions matter.
In other words, how does that comma make you feel? —Russell Harper, CMOS Shop Talk, Fiction+
People (and narrators) don't always speak in formal, grammatically correct sentences. So please, don't correct the voice out of your novel—and don't allow your editor to either! And if you've put a lot of thought into your comma usage, make sure you communicate your preferences. Editors will pay attention to your style and edit accordingly, but might end up inadvertently changing some of your deliberate comma choices if you don't give them a heads-up.
Most comma rules are agreed upon across styles, but the serial comma is the exception. Chicago Style (and most other US style guides for book publishing) favor the serial comma. AP Style does not use the serial comma unless it's needed to prevent misreading, which makes sense since space is tight in newspapers and every little bit counts. I occasionally notice AP Style commas in fiction books (this is standard in the UK), but don't recommend this style choice. However, what matters most is being consistent with whatever you choose.
Items in a series of three or more are usually separated by commas. The commas stand in for "and." When you don't use any "ands," it's called asyndeton.
I loved him madly, truly, deeply.
When you use lots of "ands," it's called polysyndeton. You can omit the commas or have "ands" and commas. Either is fine, but the rhythm and effect will be different.
I want ice cream and pizza and candy and presents and ...
But most of the time you'll use commas between the first items, and "and" before the last item in the series. The red comma before the "and is the serial comma (aka the Oxford comma).
I want ice cream, pizza, candy, and presents.
There is no comma after the final item in the series unless the syntax of the sentence requires it.
I want ice cream, pizza, candy, and presents on my birthday. ✓
I want ice cream, pizza, candy, and presents, and don't forget the piñata! ✓
Whether you're using the serial comma or not, add or omit the commas as needed to prevent ambiguity. Or even better, recast.
I ate with my mom, Hillary Clinton, and my uncle George. X (unless your name is Chelsea Clinton)
I ate with my mom, Hillary Clinton and my uncle George. ✓ (better without the serial comma)
I ate with my mom, my uncle George, and Hillary Clinton. ✓ (even better recast)
No serial comma is added with ampersands.
The law firm of Smith, Thompson & Mackenzie.
Commas and independent clauses
An independent clause contains a subject and a verb and can stand alone as a complete thought.
A comma isn't enough on it's own to join two independent clauses (this is called a comma splice) unless the clauses are short, repetitive, and closely related.
Comma splices are considered an error in formal writing, but are sometimes acceptable in fiction (for artistic reasons), and more acceptable in dialogue, where they can be useful to show certain patterns of speech. (There's a great article at CMOS Shop Talk/Fiction+ on Comma Splices and Run-On Sentences.)
The boy jumped the fence, he ran off as soon as he landed. X
"It was the best of times, it was the worst of times ..." ✓
Easy come, easy go. ✓
A coordinating conjunction (and, but, for, or, nor, yet, so) is needed in addition to the comma to prevent a comma splice.
But with short, closely related clauses, the comma can be omitted and the and used alone. In fiction, there's even more leeway with omitting the comma if it helps create the desired rhythm and emphasis.
The boy jumped the fence, and he ran off as soon as he landed. ✓
The boy jumped the fence, but he tripped and fell on the other side. ✓
He comes and he goes. ✓
When you have three short independent clauses that share a subject, it's okay to connect them with commas. This is not considered a comma splice. (Two, bad. Three, good.😉)
I came over, I ate a snack. X
I came, I saw, I conquered. ✓
Commas and dependent clauses
A dependent clause contains a subject and a verb, but can't stand alone as a complete thought. Usually because it begins with a subordinating conjunction such as if, when, until, before, after, although, etc.
Until we finish our chores to our mother's satisfaction ...
Before the rains came ...
When a dependent clause precedes an independent clause, it's generally followed by a comma.
Until we finish our chores to our mother's satisfaction, we can't watch TV.
Before the rains came, the soil was cracked and dry.
If the sentence is short and clear, you can choose to omit the comma.
Until we finish we can't watch.
When a dependent clause follows the main, independent clause, a comma usually isn't needed.
We went sailing because we had nothing better to do.
We went, before you came. X
If the dependent clause feels like an afterthought or doesn't feel essential to the meaning of the sentence, the pause a comma creates may be just the ticket.
We did go sailing, although we weren't all that into the idea.
But ... a comma may not give enough separation in this case.
We did go sailing—although we weren't all that into the idea.
Be careful with "because." If it follows a negative statement, a comma may be needed for clarity.
I didn't win the contest because of my luck. X (Did I not win, due to my bad luck? Or did I win for a reason other than luck?)
I didn't win the contest, because of my luck. ✓
I didn't win the contest because of my luck, but because I cheated. ✓
Commas after coordinating conjunctions and before parenthetical phrases
Traditionally, a comma would go before and after a coordinating conjunction that precedes a parenthetical phrase and an independent clause.
While the following example is not wrong, the commas create a choppy rhythm.
Scarlett scanned the room, and, out of nowhere, the perpetrator appeared.
It is now considered perfectly acceptable, perhaps even preferable, to leave out the second comma.
Scarlett scanned the room, and out of nowhere, the perpetrator appeared.
If the coordinating conjunction isn't separating two independent clauses, the comma goes after the coordinating conjunction.
Scarlett scanned the room and, briefly, wondered where the perpetrator had gone.
Commas with compound predicates
In general, commas shouldn't separate a subject from its verb. When the subject is a long phrase, it's easier to make this mistake.
Running all over the place trying to find ingredients, isn't my idea of a good time. X
The exception is for a pair of commas surrounding a parenthetical element.
Running, my favorite sport, has lots of health benefits.
This is still true with compound predicates (when the noun has more than one verb).
Sally took a excessively long shower and threw her clothes on over a still-wet body to make up the time. (no comma before "and")
In fiction, if a pause is desired before a subsequent verb for emphasis, inflection, or rhythm, this rule can be broken.
Sally took a super long shower, and left a wad of hair in the drain.
Though there are other, often better, ways to get the needed emphasis.
Sally took a super long shower—and left a wad of hair in the drain!
Sally took a super long shower and left a wad of hair in the drain.
Commas with compound subjects and objects
Whenever two units (except for clauses) are connected by a conjunction and branch off the same stem, don't use a comma to separate them.
Don't separate two subjects that share a verb with a comma. (Three or more will take commas).
The grand-looking main house and the shabby little guest house in the back were both covered in gray shingles.
But ... you could separate out the second subject with two commas to change the emphasis.
The grand-looking main house, and the shabby little guest house in the back, were both covered in gray shingles.
Don't separate two objects of a single verb with a comma.
She spoke about the difficulties of starting a new business and the necessity of forging ahead anyway.
But ... this rule can be broken in creative writing if separation and emphasis is desired for artistic reasons (though using an em dash is often a better choice).
She spoke about the difficulties of starting a new business, and the necessity of forging ahead anyway.
She spoke about the difficulties of starting a new business—and the necessity of forging ahead anyway
It can also be broken if adding a comma prevents misreading.
He chased the man who took his car, and yelled bloody murder. (Comma needed to show that it's the first man who yelled, not the thief.)
Introductory words and phrases
Introductory phrases are often followed by a comma, but don't always have to be.
It depends on the type and length of the phrase, its relationship to the rest of the sentence, whether leaving out the comma causes a misreading, and author preference for close (lots of commas) or open (spare use of commas) punctuation.
Introductory prepositional phrases usually require commas if they're long, but if they're short, adding commas is up the writer.
On Sunday, we went to church. ✓
On Sunday we went to church. ✓
On the last Sunday of that blistering hot summer, we went to church. ✓
Introductory participles and participial phrases usually need commas.
Trotting past the bystanders, the magnificent stallion tossed his mane.
Aggravated, she stuck out her tongue.
Incidentally, participles and participial phrases usually need commas when they follow the noun they modify as well (unless they directly follow, see second example below).
The magnificent stallion tossed his mane, snorting as he did so.
I saw a magnificent stallion snorting and tossing his mane.
Introductory participial phrases that modify the subject by way of a linking verb don't take commas.
Trotting by was the magnificent stallion of legend.
Introductory sentence adverbs/adverbial phrases are usually followed by a comma.
But if the introductory adverb modifies the verb instead of the whole sentence, no comma is needed. Your ears will guide you here. If you read the sentence with a pause after the introductory adverb, a comma is needed. For more on sentence adverbs, see my blog article "Is 'of course' always followed by a comma? Of course not!"
Actually, the full moon was last night.
Recently I ran a marathon.
Of course I want to go!
Of course, we do need to consider both sides before making a decision.
Introductory adverbial phrases that begin an inverted sentence don't take commas.
Alongside the train rode the outlaws. (inverted)
The outlaws rode alongside the train. (natural)
If the Introductory element is a dependent clause, it should usually be followed by a comma. Exceptions can sometimes be made for short clauses, and to reduce the number of commas in a compound-complex sentence with multiple clauses.
Before the rains came, the soil was cracked and dry.
Commas with parenthetical elements
Parenthetical elements can be lifted out of the sentence without significantly altering its meaning, so they're considered nonessential or nonrestrictive. As comma usage with parenthetical elements affects clarity and readability, there's very little room for creative license.