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

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.

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 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 error is unquestionably the most common grammar mistake made by people with otherwise sound writing skills. It seems that some writers think a full stop has the same effect as the neuralyzer ("flashy thing") in Men in Black (i.e., it makes readers forget everything that preceded it). Don't worry. Your readers' memories will survive your use of a full stop!

Often the idea you want to convey will be made up of more than one sentence. That's fine. Regardless of how closely linked your sentences are, you must choose appropriate punctuation between them. Remember that a sentence is a group of grammatically complete words that expresses a complete thought. A sentence contains a subject and a verb, even if one or the other is implied. (There is an entry on sentences.)

Often, a run-on error can be fixed with a full stop, 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.)

(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.)

(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. (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.)

(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.)
You know what a sentence is. Be disciplined with your periods (full stops).
  • 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. (Oscar Wilde)
  • (There's not a comma in sight. These are both correct.)
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited and printed to create exercise worksheets.

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