Run-on Sentences

Run-on sentences occur when two or more independent clauses are improperly joined. Often, in a run-on sentence, the independent clauses are simply joined without any punctuation or a coordinating conjunction. Another type of run-on that you’ve probably heard of is the comma splice, in which two independent clauses are joined by a comma without a coordinating conjunction (and, or, but, etc.).

Let’s look at a few examples of run-on sentences:

• Often, choosing a topic for a paper is the hardest part it’s a lot easier after that.
• Sometimes, books do not have the most complete information, it is a good idea then to look for articles in specialized periodicals.
• She loves skiing but he doesn’t.

All three of these have two independent clauses. Each clause should be separated from another with a period, a semicolon, or a comma and a coordinating conjunction (remember, FANBOYS):

• Often, choosing a topic for a paper is the hardest part. It’s a lot easier after that.
• Sometimes, books do not have the most complete information; it is a good idea then to look for articles in specialized periodicals.
• She loves skiing, but he doesn’t.

A run-on sentence should not just be defined as a sentence that goes on and on. Not every long sentence is a run-on sentence. For example, look at this quote from The Great Gatsby:

Its vanished trees, the trees that had made way for Gatsby’s house, had once pandered in whispers to the last and greatest of all human dreams; for a transitory enchanted moment man must have held his breath in the presence of this continent, compelled into an aesthetic contemplation he neither understood nor desired, face to face for the last time in history with something commensurate to his capacity for wonder.

If you look at the punctuation, you’ll see that this quote is a single sentence. F. Scott Fitzgerald used commas and semicolons in such a way that, despite its great length, it’s grammatically sound, as well. Length is no guarantee of a run-on sentence.

Common Causes of Run-on Sentences

We often write run-on sentences because we sense that the sentences involved are closely related, and dividing them with a period just doesn’t seem right. We may also write them because the parts seem too short to need any division, as in “She loves skiing but he doesn’t.” However, “She loves skiing” and “he doesn’t” are both independent clauses, so they need to be divided by a comma and a coordinating conjunction, not just a coordinating conjunction by itself.

Another common cause of run-on sentences is mistakenly using adverbial conjunctions for coordinating conjunctions. For example, if we were to write, “She loved skiing, however he didn’t,” we would have produced a comma splice. The correct sentence would be “She loved skiing; however, he didn’t.”