Run-ons & Comma Splices

The run-on sentence and comma splice are common punctuation errors that can create confusion in your writing.  

Run-on sentence

A run-on sentence occurs when two or more complete sentences (independent clauses) are joined with no punctuation. Here's an example:

Joseph Cornell was an innovative American artist known for his shadow boxes and collages his art became more famous after his death in 1972.

Comma splice

A comma splice occurs when two or more complete sentences are joined only with a comma, which is not strong enough punctuation.  This is an example of a comma splice:

Joseph Cornell was an innovative American artist known for his shadow boxes and collages, his art became more famous after his death in 1972.

Five Ways to Fix a Run-on or Comma Splice

1. Add a period and a capital letter

   Add a period and a capital letter to separate the sentences.
   • Joseph Cornell was an innovative American artist known for his shadow boxes and collages. His art became more famous after his death in 1972.

2. Add a comma and a coordinating conjunction

   Add a comma and a coordinating conjunction.  Coordinating conjunctions are easy to remember as F.A.N.B.O.Y.S.—for, and, nor, but, or, yet, so.
   • Joseph Cornell was an innovative American artist known for his shadow boxes and collages, but his art became more famous after his death in 1972.

3. Add a semicolon 

   Add a semicolon if the sentences are closely related.
   • Joseph Cornell was an innovative American artist known for his shadow boxes and collages; his art became more famous after his death in 1972.

4. Add a “transitional word”

   Add a semicolon and a conjunctive adverb—also known as a “transitional word”. When using a transitional word, the comma should be placed immediately after the transition. 
   • Joseph Cornell was an innovative American artist known for his shadow boxes and collages; however, his art became more famous after his death in 1972.  
   • Common Transitional Words:

5. Add a subordinating conjunction

   Add a subordinating conjunction—also known as a “dependent word”—to the beginning or the middle of the sentence.
   • Even though Joseph Cornell was an innovative American artist known for his shadow boxes and collages, his artwork became more famous after his death in 1972.
     • In the example above, the comma stays when the conjunction "even though" is added to the beginning of the sentence.
   • Joseph Cornell was an innovative American artist because he used objects and items most people would throw away in his work.
     • In this example, the comma is removed when the conjunction "because” is added to the middle of the sentence.
   • Common Subordinating Conjunctions: