1. What is a Run-On Sentence?
A run-on sentence is a sentence that combines too many independent clauses (full sentences) without proper punctuation or connecting-words. We call it a run-on sentence because it “runs on” for too long without pausing—it is missing commas, semicolons, or conjunctions to clearly separate the ideas. Run-on sentences are also sometimes called fused sentences because they “fuse” together complete sentences, but don’t do it the right way.
Sometimes, people call a very long sentence a run-on sentence, but that’s not really accurate. Grammatically, a run-on joins two or more complete sentences without using any punctuation. Sometimes they are long, but sometimes they are short.
2. Examples of Run-On Sentences
Some run-ons are missing or misusing punctuation, or missing a word to connect the ideas:
- Sally likes soccer she doesn’t like running. Run-on
You can see that this sentence has too many ideas without any punctuation! We can fix it in a couple of different ways:
- Sally likes soccer; she doesn’t like running. Correct
- Sally likes soccer, but she doesn’t like running. Correct
By adding punctuation and coordinating conjunctions, we can fix the run-on. Here’s another example:
- I woke up late I ate a muffin for breakfast then I went to school. Run-on
- I woke up late, so I ate a muffin for breakfast, and then I went to school. Correct
- I woke up late; I ate a muffin for breakfast, and then I went to school. Correct
Without the proper punctuation and connecting words, the sentence is just confusing!
3. Missing Parts of Run-On Sentences
Run-on sentences are missing punctuation, coordinating conjunctions, or both.
a. Coordinating Conjunctions
To combine two sentences (independent clauses), you should usually use a coordinating conjunction. A coordinating conjunction, like “and,” works like a link between clauses. The seven most common coordinating conjunctions are and, but, for, nor, or, so, and yet.
- Sally woke up late, so she missed the bus to school.
Also, you should note that then is not a coordinating conjunction—it’s an adverb. So, when combining independent clauses, you still need a coordinating conjunction (like and) before then:
- Sally ate breakfast, and then she went to school.
b. Punctuation
Run-on sentences are often missing important punctuation marks: semicolons or commas.
Commas
Commas (,) are important punctuation marks that tell us when to pause in a sentence. They also help to separate ideas, which is a big problem with run-on sentences: they may not have a comma(s), so they keep “running on” without pausing. When you use a comma to fix a run-on, it comes before a coordinating conjunction, like this:
- Sally went to soccer practice, and Sam went to math club.
Semicolons
Semicolons (;) connect sentences that are related to each other. It indicates that your sentence will continue with more information related to its first part. If you don’t want to use a coordinating conjunction, you can replace a comma and conjunction with a semicolon, like this:
- Sally went to soccer practice; Sam went to math club.
4. Ways to Fix Run-On Sentences
We can think of a run-on as a sentence that really wants to be a compound sentence, but it is just missing some important things! A compound sentence has two independent clauses, so the first thing to do is identify those two clauses (each will have a subject and a predicate). Then we can focus on the two main problems that cause run-ons: missing commas and conjunctions, or misusing commas when there should be a semicolon. When you fix those problems, then you have a compound sentence.
a. Fixing Run-ons with Coordinating Conjunctions
A common and easy way to fix a run-on sentence is by adding a coordinating conjunction. Here’s a basic run-on sentence:
- Sally likes blueberry muffins she eats them every day for breakfast. Run-on
You can see that this sentence runs on for too long without being broken up at all. So, let’s use a comma and a coordinating conjunction:
- Sally likes blueberry muffins, so she eats them every day for breakfast. Correct
That’s better! Now the sentence is much easier to read and understand. Let’s try another:
- Sally can’t bake muffins Sam can’t either. Run-on
- Sally can’t bake muffins, and Sam can’t either. Correct
By adding a comma and the word ‘and,’ we break up the sentence so that it is clearer.
b. Fixing Run-ons Without Coordinating Conjunctions
If you don’t use a coordinating conjunction to correct a run-on sentence, then you should use a semicolon, NOT a comma:
- Sally likes blueberry muffins she eats them every day for breakfast. Run-on
- Sally likes blueberry muffins, she eats them every day for breakfast. Incorrect
- Sally likes blueberry muffins; she eats them every day for breakfast. Correct
If you use a comma when you are supposed to use a semicolon, you get a “comma splice,” which is similar to a run-on sentence because it also misuses punctuation.
5. How to Avoid Run-On Sentences
As mentioned, a run-on tries to be a compound sentence, but fails! So, we can avoid run-ons by remembering how to properly write a compound sentence:
Compound Sentence = Independent Clause + (comma, conjunction) + Independent Clause
or
Compound Sentence = Independent clause + (semicolon) + Independent Clause
Finally, reviewing these rules can help you avoid run-ons:
A run-on sentence happens when you “run on” too long and use two or more independent clauses without pausing with a comma, coordinating conjunction, or semicolon.
You can use coordinating conjunctions (like and, but, or so) to connect independent clauses.
Commas can only connect two independent clauses if they are followed by a coordinating conjunction ( ___________, and ___________).
To combine two independent clauses without a coordinating conjunction, you need a semicolon (__________;___________.)
Using a comma instead of a semicolon to connect independent clauses causes a comma splice.
