Run-on sentences are are also called fused sentences. You are making a run-on when you put two complete sentences (a subject and its predicate and another subject and its predicate) together in one sentence without separating them properly.
Here is an example of a run-on sentence
My favorite Mediterranean spread is hummus it is very garlicky.
This one sentence actually contains two complete sentences. However, in the rush to get that idea out, I made it into one incorrect sentence. Luckily, there are many ways to correct this run-on sentence.
You could use a semicolon:
My favorite Mediterranean spread is hummus; it is very garlicky.
You could use a comma and a coordinating conjunction (for, and, nor, but, or, yet, so):
- My favorite Mediterranean spread is hummus, for it is very garlicky. -OR-
- My favorite Mediterranean spread is hummus, and it is very garlicky.
You could use a subordinating conjunction (see previous example):
- My favorite Mediterranean spread is hummus because it is very garlicky. -OR-
- Because it is so garlicky, my favorite Mediterranean spread is hummus.
You could make it into two separate sentences with a period in between:
My favorite Mediterranean spread is hummus. It is very garlicky.
You could use an em-dash (a long dash) for emphasis:
My favorite Mediterranean spread is hummus—it is very garlicky.
You CANNOT simply add a comma between the two sentences, or you will end up with what is called a “comma splice.”
Here is an example of a comma splice:
My favorite Mediterranean spread is hummus, it is very garlicky.
You can fix a comma splice the same way you fix a run-on—either change the punctuation or add a conjunction. The good news is that writers tend to be either comma splicers or run-on artists, but almost never both. Which one are you?
Finding Run-Ons
As you can see, fixing run-ons is easy once you see them—but how do you find out if a sentence is a run-on if you aren’t sure? Rei R. Noguchi, in his book Grammar and the Teaching of Writing, recommends two methods for testing your sentences. Try these two tests:
- Turn your sentences into yes/no questions.
- Turn your sentences into tag questions (sentences that end with a questioning phrase at the very end—look at the provided examples).
These are two things that nearly everyone can do easily if the sentence is not a run-on, but they become next to impossible if it is.
Look at the following sentence:
My favorite Mediterranean spread is hummus.
If you turn it into a question that someone could answer with a yes or no, it looks like this:
Is my favorite Mediterranean spread hummus?
If you turn it into a tag question, it looks like this:
My favorite Mediterranean spread is hummus, isn’t it?
The first sentence is complete and not a run-on, because our test worked.
Now, look again at the original run-on sentence:
My favorite Mediterranean spread is hummus it is very garlicky.
The yes/no question can only be made with each separate thought, not the sentence as a whole:
Is my favorite Mediterranean spread hummus? Is it very garlicky?
But not:
Is my favorite Mediterranean spread hummus is it very garlicky?
The tag question can also only be made with each separate thought, rather than the whole:
My favorite Mediterranean spread is hummus, isn’t it? It’s very garlicky, isn’t it?
But never:
My favorite Mediterranean spread is hummus it is very garlicky, isn’t it?
Unlike the complete sentence, the run-on sentence doesn’t pass these tests. When you try to turn the run-on sentence into a single question, you immediately see that the sentence has more than one complete concept. Make sure you try both tests with each of your problem sentences, because you may trick yourself by just putting a tag on the last part and not noticing that it doesn’t work on the first. Some people might not notice that “My favorite Mediterranean spread is hummus it is very garlicky isn’t it?” is wrong, but most people will spot the yes/no question problem right away.
Occasionally, you or your instructor will see an extra-long sentence and think it’s a run-on when it isn’t. Long sentences can be tiring but not necessarily wrong—just make sure that yours aren’t wrong by using the provided tests.
References:
Hacker, Diana and Nancy Sommers. A Writer’s Reference. 8th edition. Boston: Bedford/St. Martin’s, 2014.
Ruszkiewicz, John, Christy Friend, Daniel Seward, and Maxine Hairston. The Scott, Foresman Handbook for Writers. 9th edition. Boston: Pearson Education Inc, 2010.
Lunsford, Andrea A. St. Martin’s Handbook. 8th edition. Boston: Bedford/St. Martin’s, 2015.
Noguchi, Rei R. Grammar and the Teaching of Writing: Limits and Possibilities. Urbana, IL: National Council of Teachers of English, 1991.