What Is a Run-on Sentence? (with Examples)

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Run-on Sentences

A run-on sentence is a common error caused by merging two sentences without suitable punctuation. The most common run-on sentence is the "comma splice" (also known as the "comma fault"), which occurs when two sentences are inappropriately separated by a comma.

run-on sentence

Easy Examples of Run-on Sentences

These are all comma splices.
  • Cannibals don't eat clowns, they taste funny.
  • Being dyslexic has drawbacks, I once went to a toga party dressed as a goat.
  • There's one good thing about egotists, they don't talk about other people.
These would all be correct if the commas were replaced with periods (full stops).

Real-Life Examples of Run-on Sentences

The only correct comma in five examples below is the one after "however" in the last example. All the rest can be replaced with periods (full stops).
  • Only one man in a thousand is a leader of men, the other 999 follow women. (Comedian Groucho Marx)
  • Be kind to those that meet you as you rise, you may pass them again as you fall.
  • When will I learn? The answers to life's problems aren't at the bottom of a bottle, they're on TV. (Homer Simpson)
  • You can collect as many signatures as you like, the reservoir is still going to be built.
  • (Sometimes, the first sentence feels so connected to the second that a full stop might seem wrong. You have to trust yourself to know what a sentence is and be disciplined with your full stops.)
  • Lee had all the best tackle, however, he failed to catch a single fish.
  • (The word "however" is a major cause of run-on sentences. When used like a bridge between two sentences, it should start a new sentence or be preceded by a semicolon — definitely not a comma. Don't overdo the practice of using a semicolon before "however." It gets annoying pretty quickly. If your "however" is bridging two sentences, stick a capital H on it.)

Why Should I Care about Run-on Sentences?

The run-on sentence is undoubtedly the most common grammar mistake made by writers with otherwise sound writing skills.

Here are two writing tips to help you avoid run-on sentences.

(Tip 1) Write one sentence at a time and be disciplined.

A sentence is a group of grammatically complete words that expresses a complete thought. A sentence must contain a subject and a verb (even if one or the other is implied).

Often the idea you want to convey will be made up of more than one sentence. Regardless of how closely linked those sentences are, you must choose appropriate punctuation between them. You know what a sentence is. Be disciplined!
  • I love angel cake, it is my favourite.
  • I love angel cake. It is my favourite.
Remember that a comma does not mean "I haven't quite finished what I saying yet."

Read more about using commas.

(Tip 2) Consider other punctuation to end your sentence.

Often, a run-on error can be fixed with a period, but, without rewording, there are four other possible fixes, all of which are worth having in your writer's toolbox.

(1) Use a semicolon:

  • Duty is what one expects from others; it is not what one does oneself. (Playwright Oscar Wilde)
  • (Using a semicolon gives smoother transition between sentences than a full stop.)
Read more about using semicolons.

(2) Use three dots:

  • It's not true that I had nothing on…I had the radio on. (Actress Marilyn Monroe)
  • (Using three dots (also called ellipsis) gives a pause for effect.)
Read more about using ellipsis.

(3) Use a colon (if appropriate, which it probably won't be):

  • I have made an important discovery: alcohol, taken in sufficient quantities, produces all the effects of intoxication. (Playwright Oscar Wilde)
  • (If sentence 2 is an expansion of something in sentence 1, you can use a colon. A colon is like an equals sign. Here, "important discovery" equals sentence 2.)
Read more about using colons.

(4) Use a dash:

  • Please do not shoot the pianist — he is doing his best.
  • (A dash looks a bit stark, but the dash is very versatile. It could replace the semicolon, the three dots or the colon in the three examples above.)
Read more about using dashes
Final Advice

You know what a sentence is. Be disciplined.
Looks at these two correct examples. There's not a comma in sight.
  • Age is not a particularly interesting subject. Anyone can get old. All you have to do is live long enough. (Comedian Groucho Marx)
  • I always pass on good advice. It is the only thing to do with it. It is never of any use to oneself. (Playwright Oscar Wilde)
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

See Also

More about run-on errors and comma faults Extend a sentence with a semicolon What is a sentence? What are coordinating conjunctions? What are subordinating conjunctions? Glossary of grammatical terms