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Identifying and Fixing Run-On Sentences




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In writing, run-on sentences are a common problem caused by not constructing sentences properly. In this lesson, you will learn about three types of run-on sentences: fused sentences, comma splices, and polysyndeton.

What Is Run-On Sentence?

Run-on sentences refer to a type of writing error resulting from writing independent sentences without connecting them properly. There are three common types of run-on sentences: fused sentences, comma splices, and polysyndeton. The first two have their own pages and exercises.

Fused Sentences

Fused sentences happen when you write two complete, independent sentences as a single sentence without either using punctuation to separate them or using no coordinating conjunctions to combine them into a single sentence. Below is an example of simple fused sentence:

The instructor was disappointed in his students they did not turn in their work on time.

Both sentences (“The instructor was disappointed in his students” and “They did not turn in their work on time”) are fused into a single sentence. This generally causes your readers to hesitate trying to understand your ideas.

Comma Splices

Another type of run-on sentences, comma splices, occur when you incorrectly use a comma to join two complete, independent sentences. You should use terminal punctuation (i.e., periods, question marks, or exclamation points) to end a complete sentence.

Below is a typical example of a comma splice:

He has not chosen his major yet, he is still confused what he wants to do after college.

Again, in the above example, you have two independent sentences, so they should be separated by a comma. Instead, a comma is improperly used, creating a comma splice.


Polysyndeton is another common type of run-on sentences. It occurs when you write several sentences using coordinating conjunctions in the same sentence. In the example below, notice how many conjunctions are used (“and,” “so” and “but”), resulting in a long difficult-to-read sentence.

When people hear an accent, they make assumptions about the speaker, and the accent triggers stereotyped perceptions based on them, but stereotypes are inaccurate, so accented speakers are discriminated against, so people should be aware of their own biases.

An easy way to correct polysyndeton errors is to break the sentence down into shorter, easier-to-understand ideas. For example, you could write,

When people hear an accent, they make assumptions about the speaker. The accent, in turn, triggers stereotyped perceptions based on these assumptions. As a result, accented speakers are discriminated against because stereotypes are inaccurate. People should be aware of their own biases.

When you revise your work, pay close attention to long sentences, particularly those connected by an overabundance of conjunctions. It is okay to have a variety of long and short sentences; however, stringing many ideas as in the above example makes you writing difficult to read and amateurish.

Identifying and Correcting Fused Sentences and Comma Splices

After reading this page, learn how to identify and correct run-on errors so you can improve the quality of your written work.

Fixing fused sentences (includes practice)
Fixing comma splices (includes practice)



  1. This practice is fairly advanced, so it should be helpful to complete the following lessons first as they go deeper into run-on sentences:
  2. Complete Identify run-on sentences (fused sentences and comma splices) when you feel fully prepared.

Related Lesson

The following lesson is related to identifying sentence issues while editing your writing.

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