How to fix run-ons, comma splices, and fragments  

If you need for a quick fix for a sentence error, scroll down to the "Sentence Errors" section. To understand how to recognize and avoid these sentence errors, you’ll need to know about the fundamental building block of sentences: the clause.


A clause is a group of words that contains a subject that performs a verb. Here are examples of  clauses, with the subject and verb bolded:  

  • Birds fly.
  • After Esther spoke 
  • The man ate the salad.
  • Jess began to edit.  
  • Because the cat meowed
  • When the essay was finished 
  • Once it started raining
  • My phone rang 

Clauses come in two types: independent and dependent.

An independent clause is a clause that forms a complete thought. In the above examples, the independent clauses have periods because independent clauses form complete sentences.  

A dependent clause is a clause that does not form a complete thought and is marked by a dependent word like when, once, because, after, as, unless, or while. Dependent clauses must be attached to an independent clause to form a complete sentence. Sentences can have multiple dependent clauses.  

Sentences with both independent and dependent clauses are called complex sentences.  In these complex sentences, the dependent clauses are bolded.  

  •  She knew it was fall because the leaves were orange 
  • While he was jogging, he noticed something strange. 
  • Though it was time for his speech, the governor was nowhere to be found.   
  • After Esther spoke, Jess began to edit because she was excited 
  • I will sing when I drive home after I finish this job.  


Like dependent clauses, phrases don’t form a complete sentence unless they areattachedtoanindependent clause. A phraseis any group of words that doesn't have a connected subject and verb.  Here are some examples of phrases: 

  • beside the white chickens
  • to plant a tree  
  • every Sunday
  • the largest living species
  • rejecting the decision
  • the idea of  listening to a long, boring story

Sentence Errors  

Run-on Sentences

A run-on sentence is a sentence with improperly linked independent clauses. In order to create a sentence with more than one independent clause, called a compound sentence,the independent clauses must be connected with a comma and one of the seven coordinating conjunctions(and, but, so, for, or, yet, and nor).  

  • I like pie I baked one yesterday. (run-on)           
  • I like pie, and I baked one yesterday. (compound sentence) 

Comma Splices

A comma splice is a type of run-on where independent clauses are incorrectly linked with a comma but no conjunction. To fix a comma splice, add a coordinating conjunction or create two separate sentences.   

  • I like pie, I baked one yesterday. (comma splice) 
  • I like pie, and I baked one yesterday. (correct compound sentence) 
  • I like pie. I baked one yesterday. (two correct sentences) 

Run-ons (including commas splices) can also be fixed with a semicolon, if you’re feeling fancy.  

  • I like pie; I baked one yesterday 

Sentence Fragments

A sentence fragment is acollection of words with no independent clause. Often fragments are dependent clauses. Fragments can be used stylistically in some genres, butare usually avoided in formal academic writing. Here are examples of different kinds of sentence fragments: 

  • Because of the good weather.

Dependent clause

  • Ran away from the rolling boulder.

No subject

  • Explaining the short line.


  • Jack and Jill.                  

No verb   

  • The book, which I found entertaining despite the many tables andcharts. 

No verb attached to the subject (book).  

  • In the beginning, which is where Shakespeare tells us the story is set in Verona, says "Where civil blood makes civil
    hands unclean."

No subject attached to the verb (says).

Practical Application

Your actual writing is probably much more complicated than these examples. To find and fix errors in long, tangled sentences, start by sorting clauses into independent and dependent. Then, see if those clauses are interacting with each other properly. Is there a lonesome dependent clause, leaving you with a sentence fragment? Are there sentences with multiple independent clauses, and if so, are the independent clauses connected with a comma and a conjunction (or a semicolon)?  

If you’re having trouble identifying sentence errors in your writing, you aren’t alone. Writing Center tutors are a great resource for quickly finding and fixing sentence errors! Come talk clauses and commas with us!