Introduction to Run-ons


Remember the basic sentence? A basic sentence has a subject, verb, and other details that express a complete thought.

A run-on is more than one complete sentence joined together and punctuated as a single sentence. A run-on is missing the punctuation and sometimes words that correctly join these complete sentences.

To correct a run-on, join the two complete sentences by using one of these options:

Or, correct a run-on by separating the complete sentences.


The video will show subjects underlined once in purple and verbs underlined twice in green. These colors and lines can help you think through the parts of the word group. Watch to see how color-coding can help you find run-ons.

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Writers sometimes create run-ons when they try to keep closely related ideas together within the same sentence. For example, in the sentence below, the writer is trying to explain that his boss liked his idea so much that she will forward it to the board of directors. Joining the two sentences makes sense because of the close relationship of the ideas; however, the writer has not used the correct punctuation.

When the two sentences are put together without any punctuation at all, the run-on is called a fused sentence.


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When the two sentences are put together with only a comma, the run-on is called a comma splice.


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A comma alone is not enough to join these two sentences:

Correcting a run-on means adding correct punctuation. For instance, replacing a comma with a semicolon (;) between the two sentences is an appropriate revision.


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Other ways of correcting run-ons require adding punctuation and sometimes words:

The easiest method of correcting a run-on, however, is to separate the sentences.

In your writing, be aware of your options for joining complete sentences. Keeping closely related ideas together in one sentence requires careful punctuation.


The study pages explain the different types of run-ons and corrections in more detail. As you read through the study pages and then practice with LearningCurve before taking the post-test, see if you can identify the subject and verb in each word group; next, determine if the sentences are joined correctly.

Looking for complete sentences that are correctly joined will help you identify and correct run-ons for the post-test and in your own writing. Checking for complete sentences will also help you with other units in LaunchPad Solo for Readers and Writers.

Don’t forget to work smartly!