Free Grammar Help—Sentences— Run-on Sentence

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A run-on sentence is a sentence with two (or more!) complete thoughts that are run together with no adequate sign to mark the break between them. Two kinds of run-on sentences are fused sentences and comma splices.

Fused Sentences

Some run-ons have no punctuation at all to mark the break between the thoughts. Such run-ons are known as fused sentences: they are fused, or joined together, as if they are only one thought. Some teachers mark fs in the margin of a paper to indicate: fused sentence.

Fused Sentence Examples

My grades are very good this semester my social life rates only a C.

Our father was a madman in his youth he would do anything on a dare.

I love music Lady Gaga is my favorite artist.

Our dog is such a goofball he often chases his tail.

Comma Splices

A comma can be used to join two parts of a sentence, but if the two parts are strong enough to stand on their own, then a comma is not strong enough to join them.

In run-on errors known as comma splices, a comma is used to connect or “splice” together the two complete thoughts. Some teachers mark cs in the margin of a paper to indicate: comma splice.

If you have a very long sentence with lots of commas in it, you have probably written a sentence with a comma splice error.

Comma Splice Examples

My grades are very good this semester, my social life rates only a C.

Our father was a madman in his youth, he would do anything on a dare.

I love music, Lady Gaga is my favorite artist.

Our dog is such a goofball, he often chases his tail.

Comma splices are the most common kind of run-on mistake. Students sense that some kind of connection is needed between two thoughts, and so put a comma at the dividing point. But the comma alone is not sufficient, and a stronger, clearer mark between the two thoughts is needed.

Three common methods of correcting a run-on sentence:

1. Use a period and a capital letter to break the two complete thoughts into separate sentences.
   My grades are very good this semester. My social life rates only a C.
   Our father was a madman in his youth. He would do anything on a dare.
   I love music. Lady Gaga is my favorite artist.
   Our dog is such a goofball. He often chases his tail.
2. Use a comma plus a joining word (conjunction: and, but, for, or, nor, so, yet) to connect the two complete thoughts.
   My grades are very good this semester, but my social life rates only a C.
   Our father was a madman in his youth, for he would do anything on a dare.
   I love music, and Lady Gaga is my favorite artist.
   Our dog is such a goofball, because he often chases his tail.
3. Use a semicolon to connect the two complete thoughts.
   My grades are very good this semester; my social life rates only a C.
   Our father was a complete madman in his youth; he would do anything on a dare.
   I love music; Lady Gaga is my favorite artist.
   Our dog is such a goofball; he often chases his tail.

A fourth method of correcting a run-on is to use subordination using a coordinating conjunction. See conjunctions.