Of all punctuation marks, commas are the ones that are the least understood/most misused
because they have multiple usages, and not all of them are extremely clear.
In general, commas can be divided into separate categories:
Whenever you have three or more items in a list, commas are needed to separate these items.
Example: I went to the store to buy milk, bread, and eggs.
Whenever you are separating items that have commas within them (e.g. city and states), these
commas are changed to semicolons.
Example: I have lived in Baton Rouge, Louisiana; Denver, Colorado; and Clarksville,
Tennessee.
Whenever you have two or more adjectives describing one noun, a comma goes in between the
two adjectives.
Example: There is a big, beautiful tree standing in the field.
Take caution for cases when you have two or more words that are actually functioning as
one descriptor. When you have these, a hyphen is needed. One way to check is to add
the word and. If it makes sense, use a comma; if it doesn’t, use the hyphen.
Example: My second-grade students love to read Clifford, the Big, Red Dog.
Parenthetical expressions are expressions that occur in the middle (or beginning of sentences)
that supply additional information; these phrases are needed for the sentence to make sense
contextually but not grammatically. Whenever you have these parenthetical expressions,
remember that commas need to go on both sides of them.
These words or phrases describe or rename nouns that appear right before them.
Example: I like to walk Fido, my dog, in the morning.
Example: My dad, a man who has been working his entire life, just retired.
Whenever you are separating items in a list that also have appositives within them, the commas
separating the items in the list become semicolons.
Example: My mom, Linda; my dad, George; and my sister, Susanna; all graduated from the
same university.
Comma Usages
Resource: Much of the information in this handout is paraphrased from a handout created by Jerry W.
Passon.
Commas with lists and adjectives
Parenthetical expressions/ dependent clauses
Appositives
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Comma Usage
Dependent clauses are clauses that add supporting information to a sentence but cannot stand
alone; these clauses rely on another part of the sentence to make sense.
Whenever these clauses are located at the beginning of the sentence, commas are needed to both
separate them from the main clause and also combine them with the information located within
the main clause.
Subordinating conjunctions are words that set up dependent clauses at the beginning of
sentences. Some examples of these include
Whenever you use one of these words at the beginning of the sentence, commas always go
after them; these commas are generally placed before the subject of the main clause.
Example: After I arrived at the baseball field, it started to rain.
Example: Since I was a little kid, I’ve wanted to go to Disney World.
Whenever these phrases come at the end of a sentence, no comma is used.
Example: It started to rain after I arrived at the baseball field.
Participles (verb form ending in –ing) can serve many functions within a sentence; they can be
nouns (running is fun), adjectives (the panting dog belongs to the doctor), or verb forms setting
up dependent clauses. Like subordinate clauses, these also need commas separating them from
the rest of the sentence.
Example: Looking at the sunrise, I discovered the meaning of life.
Dependent clauses
Participial phrases
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Comma Usage
However, remember that whenever you place the comma, what comes to the right of it should be
a complete sentence. If it is not, then no comma will be used.
Example: Standing at the doorway, was a man. (was a man is not a complete sentence.)
Example: Standing at the doorway was a man. (Standing at the doorway is the subject of
this sentence, so the comma is not needed.)
Whenever these participial phrases are at the end of the sentence, a comma is only placed before
them when the noun that phrase is modifying appears anywhere in the sentence other than
immediately before it.
Example: I saw a man standing in the doorway.
Example: I sat in the library, waiting for my appointment at the Writing Center.
Whenever you have a prepositional phrase at the beginning of the sentence, commas can actually
go after those phrases as well; with these, the comma becomes obligatory if the phrase is longer
than three words. Also, if you have multiple prepositional phrases in a row, then the comma will
go after the last one.
Example: In the morning, I ran a 5K.
Example: In the morning I ran a 5K.
(Both are acceptable)
Example: During a heavy thunderstorm, the dog jumped under the bed.
Example: In the middle of summer, my town holds their annual festival.
Much like the subordinate clauses above, whenever you have a prepositional phrase at the end of
a sentence, no comma is used to separate it.
Example: I was born during the month of May.
There are certain transitional words, such as however, nevertheless, therefore, etc., that will
always take a comma after them when they appear at the beginning of a sentence. When they
appear in the middle of the sentence, the comma will appear on both sides of the word.
Example: I am tall; however, I still couldn’t ride the roller coaster.
Example: I may like pizza, but I don’t, however, like pineapple on my pizza.
Prepositional phrases
Transitional words
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Comma Usage
The most common use for commas are with the coordinating conjunctions. These seven
conjunctions can be remembered by the acronym FANBOYS: For, And, Nor, But, Or, Yet, So.
These conjunctions are used to combine two separate ideas. However, commas are only used
before these conjunctions if both sides of the conjunction contain COMPLETE sentences.
In order for a comma to be used, each side of the conjunction should be able to stand on its own.
You can test this by momentarily changing the conjunction to a period. Then, check to see if
what comes on both sides of that period contain at least a subject and a verb and are independent
clauses.
Example: I might have been able to continue my studies but something inside of me told me
that I should start working once I get my bachelor’s degree.
Example: I might have been able to continue my studies. Something inside of me told me
that I should start working once I get my bachelor’s degree.
Example: I might have been able to continue my studies, but something inside of me told
me that I should start working once I get my bachelor’s degree.
In the instance where one side is not a complete sentence, no comma will be used in front of the
conjunction. Follow these same steps, and you should be able to differentiate between the two.
Example: It is a small yet spacious car.
Example: I love riding my bike and walking around the fjords.
Coordinating Conjunctions
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Comma Usage
