Run-Ons

A run-on is two or more complete sentences (also called independant clauses) joined together without a proper connection. Run-ons are one of the most common grammatical errors in student writing. 

There are two different types of run-ons: fused and comma splice.

A fused run-on is two sentences put together with NO punctuation. 

Fused Run-on

Fabio loves cats he loves dogs even more.

Fused Run-on

Cheese is Sarah's favorite food she eats it every day.

The most common kind of run-on is a comma splice, which is two sentences linked together with a comma:

Comma splice

Fabio loves cats, he loves dogs even more.

Comma splice

Luisa didn't want to go to the movies, her friends wanted her to go. 

Recognizing Run-Ons

Sometimes it can be difficult to identify run-ons in your own writing. Many people believe that any long sentence is a run-on, but this is not the case. It is possible to have very long sentences that are not run-ons and very short sentences that are run-ons. 

run-on

Bill loves me I love him, too.

not a run-on

Although Bill loves me and I love him, I worry that perhaps our love will not be enough to sustain us through today's difficult world, in which so many previously happy couples are driven to deception, infidelity, and ultimately divorce.

While the second sentence is long and confusing, it is not grammatically incorrect. Every part of the sentence has been linked properly, and there is no place that the sentence could be split into two halves that could both stand alone as sentences. On the other hand, the first sentence can be split into two halves that could each stand alone as a sentence:

Sentence One	Sentence Two
Bill loves me.	I love him, too.

When trying to determine if a sentence is a run-on or a correct, consider the following questions:

1. Could the sentence be split into two halves that could each stand alone as a sentence?
   • If yes, then it is a run-on.
   • If no, then it is not a run-on.
2. Is there a comma in the sentence? If so, could the material on each side of the comma stand alone as a complete sentence?
   • If yes, then it is a comma splice.
   • If no, then it is not a comma splice.

Fixing Run-Ons

There are five main ways to fix run-ons:

1. Add a period.
2. Add a semicolon.
3. Add a coordinator. 
4. Add a subordinator. 
5. Add transition word. 

Add a Period

The simplest way to fix a run-on or comma splice is by dividing it into two separate sentences.

Run-Ons	Corrected Sentence(s)
Cheese is Sarah's favorite food, she eats it every day.	Cheese is Sarah's favorite food. She eats it every day.
Rachel doesn't like to eat cheese, she is lactose intolerant.	Rachel doesn't like to eat cheese. She is lactose intolerant.

Add a Semicolon

You may find that sometimes you would like to connect two sentences together because their ideas are closely connected. One way you can do this is with a semicolon, which looks like a comma with a dot on top of it. A semicolon links two complete sentences, so it is a perfect way to correct a run-on or comma splice.

Run-Ons	Corrected Sentence(s)
Cheese is Sarah's favorite food, she eats it every day.	Cheese is Sarah's favorite food; she eats it every day.
Fred is not angry, he just expresses his opinions loudly.	Fred is not angry; he just expresses his opinions loudly.

Mistakes with Semicolons

There are a couple of common mistakes to watch out for when using semicolons.

1. Semicolons are considered special punctuation and should not be used too often. Try to limit yourself to one semicolon per paragraph unless you have a good reason to use more.
2. Semicolons should only be used to connect two complete sentences. Be careful not to use a semicolon to connect a partial sentence. Instead, use either a comma or no punctuation at all, depending on the structure of the sentence.

Incorrect Semicolon Use	Corrected Sentence
Bill loves crackers; because they are crispy.	Bill loves crackers because they are crispy.
Knowing that she was late for work; Kate snuck in the back door.	Knowing that she was late for work, Kate snuck in the back door.
Juan loves movies including; Juno and No Country for Old Men.	Juan loves movies including Juno and No Country for Old Men.

 

Add a Coordinator

A third way to fix a run-on is by adding a coordinator (a type of linking word) to link the two complete setences together. The coordinator goes between the two sentences, preceded by a comma. 

Run-Ons	Corrected Sentence(s)
Fabio loves cats he loves dogs even more.	Fabio loves cats, but he loves dogs even more.
Cheese is Sarah's favorite food, she eats it every day.	Cheese is Sarah's favorite food, and she eats it every day.

There are only seven coordinators: for, and, nor, but, or, yet, so. They spell out the word FANBOYS. Each coordinating conjunction shows a different relationship between sentences. Use the definitions and examples below to help you understand how each coordinating conjunction is used in a sentence.

• For (effect/cause): Jasmine is afraid of dogs, for she was bitten by a dog when she was young.
• And (addition):  Isaiah lives in Livermore, and his parents live nearby in Pleasanton. 
• Nor (addition of negatives): Mary doesn’t want to go to college, nor does she want to find a job.
• But (contrast): Abdul likes to read, but he prefers to watch television.
• Or (alternative): Jose thinks he wants to study math, or he might be interested in fire fighting.
• Yet (contrast): Justin really likes to run in the morning, yet he hates getting up early.
• So (cause/effect): Maria loves dogs, so she went to the animal shelter to adopt one.

 

 

Add a Subordinator

Subordinators (a type of connecting word) can be attached to either the first or second half of the sentence. If they are attached to the first half of the sentence, you must include a comma before the second half of the sentence to show where it splits.

Run-Ons	Corrected Sentence(s)
Fabio loves cats he loves dogs even more.	Although Fabio loves cats, he loves dogs even more.
Boris forgot to bring his wallet, he had to run home and get it.	Because Boris forgot to bring his wallet, he had to run home and get it.
Camilla got sick she had to stay home from work.	When Camilla got sick, she had to stay home from work.

If the subordinator is attached to the second half of the sentence, no comma is needed in most cases.

Run-Ons	Corrected Sentence(s)
Lucille is friendly she is shy at first.	Lucille is friendly although she is shy at first.
Rachel doesn't like to eat cheese, she is lactose intolerant.	Rachel doesn't like to eat cheese because she is lactose intolerant.
Lisa used the hammer she found it in the drawer.	Lisa used the hammer after she found it in the drawer.

 

Common Subordinators 

Subordinator	Relationship/Meaning
although, even though, though, whereas, while	contrast
since, because	cause/effect
if, unless	condition
after, as soon as, before, whenever, when, until	time

Add a Transition Word 

One last way to correct a run-on is with a transition word (also called a conjunctive adverb).  To connect two sentences, transition words must be punctuated with a semicolon and a comma.

Run-On	Corrected Sentence
Randy left work early for the concert, he did not know it was canceled.	Randy left work early for the concert; however, he did not know it was canceled.
Sarah is allergic to nuts, she didn't eat the cookies.	Sarah is allergic to nuts; therefore, she didn't eat the cookies.
My teacher assigned many great novels, we read Beloved by Toni Morrison.	My teacher assigned many great novels; for example, we read Beloved by Toni Morrison.

Common Transition Words

Transition Word	Relationship/Meaning
however, in constrast, on the other hand, instead	contrast
therefore, thus	cause/effect
for example, for instance	general to specific
moreover, in addition, similarly	addition

 More Resources 

RAW Center Handout: Run-Ons