Run-on sentence

A run-on sentence (i.e., fused sentence), is a sentence consists of at least two independent clauses (i.e., complete sentences) are integrated together without appropriate punctuation or conjunction. Although it is frequently used in oral English and it can also be found in literature as a rhetorical device, a run-on sentence is grammatically incorrect. A run-on sentence may give readers the impression of disorganization, as well as confusion. Consequntly, such error should be avoided in writing.
There is no definite link between the length of a sentence with the fact that it is run-on. A sentence such as "The bus comes let's go" is commonly used in daily life, which is however a run-on sentence.
Some people, like Jose A. Carillo, regard run-on sentences as a serious, annoying grammar violation of all the flawed English. "This is because I’m pretty sure that they aren’t just run-of-the-mill grammar errors arising from haste or oversight but a disturbing sign of an inadequate grasp of how the English language works."(1)

Comparison to correct sentences

In order to understand the grammatical incorrectness of a run-on sentence, it is helpful to study the normal forms of correct sentences, which is characteristized by using conjunctions and can be classified into several catagories.
Although there is a mixed variety of sentences, run-on sentences belong to none of them for its violation to grammtical rules.

The use of conjunctions

A conjunction is a word that "connects parts of sentences, phrases or clauses"(2), which plays a crucial role in forming logical sentences. Basically in a run-on sentence, clauses are smooshed together without conjunctions. With the absent of appropriate conjunctions, such sentence can cause misunderstanding.The chart below demonstrates some common conjunctions used in different situations.
presents non-contrasting item(s) or idea(s)
and, (and)then, as well as, both…and, not only…but also, either…or, neither…nor
presents an alternative item or idea
presents a contrast or exception
but, yet, however
presents a consequence
for, so,therefore,hence
presents a comparison
He tried to catch the bus he failed. (×)
He tried to catch the bus, but he failed. (√)

Sentence types

A sentence may comprise a number of clauses, independent or dependent ones. According to such classification, sentences can be divided into mainly four types. In simple words, each independent clause has subject and a verb; each one of them also express one thought. A run-on sentence, however, may have several subjects, verbs and thoughts in one clause, making it belong to none of the following four types of grammatically correct sentence.

1.Simple sentence

A simple sentence is "a sentence with one independent clause and no dependent clauses"(3).
She is fond of shopping.
They are close friends.

2.Compound sentence

A compound sentence is "a sentence with multiple independent clauses but no dependent clauses"(4).
The river is shallow, but he dare not swim across it.
The rain stops, and the children go out to play.

3.Complex sentence

A complex sentence is "a sentence with one independent clause and at least one dependent clause"(5).
The file had begun when we arrived at the cinema.
Henry ran his home in no time, only to find a note read that the whole family went to the hospital.

4.Complex-compound sentence

A complex-compound sentence is "a sentence with multiple independent clauses and at least one dependent clause"(6).
If you want she to join your birthday party, you'd better inform her immediately, for she may be quite busy next week.

Comma splice

The comma splice is a typical error that can be found in a run-on sentence, which "runs on from one independent clause to the next with only a comma to keep them apart"(7).
He looked tired, he had stayed up all night. (×)
He looked tired; he had stayed up all night. ()
The only difference between run-ons and comma splices is a comma. A run-on is two sentences joined without any intervening punctuation (Desi likes Lucy Fred likes Ethel). A comma splice is two sentences mistakenly joined by only a comma (Desi likes Lucy, Fred likes Ethel)(8).

Acceptable uses of the comma splice

Be aware of the following exceptions to the traditional rules against the comma splice.
1. Between each two phrases of three or more parallel clauses, which is common in literature, comma can be used to produce a rhythm or express a group of closely related meaning.
I came, I saw, I conquered.
Students in India demonstrate against the use of English, Vietnamese reformers protest against the use of French, young Israelis have no use for the languages once spoken by their parents.(9)
2.Some modern writers use the comma between two clauses when the logical connection or similarity in structure is especially close. For instance, "there may be a close cause-and-effect relationship, or a carefully balanced contrast"(10).
The fire was dead, the ship was gone. —— William Golding, Lord of the Flies
The grass is rich and matted, you cannot see the soil. —— Alan Paton, Cry, the Beloved Country


Although run-on sentences seems to be minor mistakes, one may make during the writing process, it is however essential to correct it to facilitate the communication. There are at least four ways to fix it.
1.Break the run-on sentence into two or more separate sentences:
Run-on: It was a nice day they went hiking.
Revised: It was a nice day. They went hiking.
2.Connect two independent clauses with a comma(sometimes a comma can be omitted) and a coordinating conjunction:
Run-on: It was a nice day they went hiking.
Revised: It was a nice day, and they went hiking.
3.Use a semicolon or a dash between two independent clauses:
Run-on: It was a nice day they went hiking.
Revised: It was a nice day; they went hiking.
4.Join two independent clauses with subordinary conjunction:
Run-on: It rained heavily they went hiking.
Revised: Although it rained heavily, they went hiking.

Exercises on Run-on Sentence

The Academic Center of University of Houston- Victoria provides three exercises about this subject, including revising run-on sentences and comma splices and the appropriate use of punctuation. For more information, see
Similar exercises can be found in Iliff,
Other exercises:


2.Longman Dictionary of Contemporary English. Beijing: Foreign Language Teaching and Research Press, 2005.
7.Guth, Hans P. Words and Ideas: a Handbook for College Writing. 3rd ed. Belmont: Wadsworth, 1972.
9.Guth, Hans P. Words and Ideas: a Handbook for College Writing. 3rd ed. Belmont: Wadsworth, 1972.
10.Guth, Hans P. Words and Ideas: a Handbook for College Writing. 3rd ed. Belmont: Wadsworth, 1972.

External links

Run-on Sentences, Comma Splices
Fixing Comma Splices