Run-on sentences

Contributor: Isabella Cumins 

How to recognize a run‐on sentence

A run‐on sentence is two or more independent clauses joined together with insufficient punctuation. This means that there are two or more complete sentences fused into one sentence.

  • Example: I’m in college I study chemistry.

What is a comma splice?

A comma splice generally occurs when the writer tries to fix a run‐on sentence by only adding a comma. This is called a comma splice

  • Example: I’m in college, I study chemistry.

How to avoid a comma splice

A comma splice can be avoided by adding a coordinating conjunction (for, but, and, so, nor, etc.) or subordinating conjunction (because, unless, although).

  • Example: I’m in college, and I study chemistry.

Other ways to fix a run‐on sentence

Use a semicolon: These can be used to connect two clauses that share a relationship.

  • Example: I’m in college; I study chemistry.

Use a period: a period effectively separates two clauses, whether they’re related or not.

  • Example: I’m in college. I study chemistry. (related)
  • Example: I’m in college. I work at Whole Foods. (unrelated)

Use a colon: a colon should be used to join two sentences only when the second sentence explains the first sentence.

  • Example: “Life is like a box of chocolates: you never know what you’re gonna get.” ‐ Forrest Gump

The don’ts of fixing run on sentences

  • Don’t: Go overboard on incorporating colons or semi‐colons, as they can negatively impact the clarity and focus of your writing.
  • Don’t: Forget to keep sentence variety in mind! Overusing periods to break up sentences or repetitive use of commas and conjunctions greatly affects the style of your writing.
  • Don’t: Default to dropping in a comma every time you want to pause. Improper use of a comma can result in a comma splice, as well as alter meaning.


Mignon Fogarty. (2010, August 26). What Are Run‐On Sentences? [web log post]. Retrieved from‐are‐run‐on‐ sentences?page=1

(n.d.). Comma Splices, Fused Sentences, and Run‐ons [web log post]. Retrieved from‐writing‐lab/grammar/comma‐splices.php

The Writing Center, University of North Carolina at Chapel Hill. (n.d.). Semi‐colons, colons, and dashes. Retrieved from‐and‐tools/semi‐colons‐colons