LEOLEO: Literacy Education Online

Avoiding Comma Splices, Fused Sentences, and Run-Ons


Comma splices, used sentences, and run-ons occur because two complete sentences (independent clauses) are joined incorrectly.

Comma splice

Comma splices are two complete sentences that are joined with only a comma.



Fused sentence

Fused sentences are two sentences joined together with nothing between them.



Run-on

Run-ons are two sentences joined together with only a coordinating conjunction.



These are inappropriate ways to join sentences together because readers need a signal that one main clause is ending and another is beginning.

two autos at stop light with 
semicolon on light


If the correct signal is not present, a reader can become momentarily confused, and the sequence of ideas will become difficult to follow. In essence, the sentences will crash.

two autos crashed into each 
other



To correct this problem, you can think of complete sentences as individual "scenes" that can be arranged in five different ways.

  1. Separate the clauses with a period. This is the strongest method of separating sentences.


  2. You can join the clauses with a semicolon if you want to separate the two sentences but still keep their ideas close together.


  3. Sometimes, you may want to make the second sentence relate to the first. You can use a semicolon with a relationship word (conjunctive adverb) followed by a comma.


  4. You can also use a comma with a coordinating conjunction. These must be used together in order to create the strong separation needed between the two sentences.


  5. You can make one sentence part of, or subordinate to, the other sentence by adding a subordinator. If a subordinator is placed before the first sentence, you will need to insert a comma after the first sentence.



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LEO:  Literacy Education Online

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Last update: 15 November 2004

URL: http://leo.stcloudstate.edu/ punct/avcsfsro.html