The Run-On Sentence:
Use Correct Grammar & Avoid It

A run-on sentence is bad news, folks. It's two or more independent clauses that are not separated with a colon, semicolon, or period. A clause is a group of words with a subject and a verb. Remember that a subject tells us whom or what the sentence is about, and the verb tells us what the subject is or does. Did you notice that two of those example clauses gave a complete thought, and two of them gave an incomplete thought?

All of them were clauses, but there are two types of clauses!

1. Independent clauses have a subject and a verb AND they can stand alone because they tell a complete idea. (I went home. & She swims.)

2. Subordinate clauses (also called dependent clauses) have a subject and a verb, but they DON'T tell a complete idea. (When I went home & Whenever she swims)

They cannot stand alone, so they need to be attached to an independent clause. Run-on sentences are made of two or more independent clauses that are not separated with a colon, semicolon, or period.

Remember the example from the top of the page? This is a run-on because it consists of two independent clauses that are not punctuated properly.

Independent Clause #1: My dog is cute.

Independent Clause #2: His name is George.

Both of those clauses have a subject and a verb, and they tell a complete idea.

You can't squish them both together without any punctuation. That is simply illegal in the world of grammar. There are three ways that you are allowed to separate two independent clauses.

1. Semicolon

I admit it. I kind of feel like the semicolon is a hoity-toity punctuation mark. (That means it's snobbish.)

But, hey, it's legit.
My dog is cute; his name is George.
2. Comma + Coordinating Conjunction

Be sure to add a coordinating conjunction between the clauses. When you only add a comma, it's called a comma splice, and you should avoid those.
My dog is cute, and his name is George.
3. Period
My dog is cute. His name is George.

That's it! Just use any of those three ways to separate independent clauses, and you'll be golden! Use this grammar quiz on fragments and run-on sentences.

You'll find everything you need to test yourself or your students. Now it's time for you to learn about sentence diagramming!