How Do You Fix a Run-On Sentence?

A run-on sentence has nothing to do with how long it is. It is entirely about structure. A run-on occurs when two independent clauses are joined incorrectly. An independent clause is a group of words with a subject and a verb that can stand alone as a complete sentence.

There are two main types of run-ons. The first is a fused sentence, where two complete thoughts are pushed together with no punctuation at all. The second is a comma splice, where two complete thoughts are connected with just a comma, which is not strong enough on its own to hold them together.

Once you identify the two independent clauses, you have four reliable ways to fix the connection.

1. Make two separate sentences. Use a period and a capital letter. This is the simplest fix.
2. Use a semicolon. A semicolon works like a weak period. It joins two independent clauses that are closely related in meaning.
3. Use a comma and a coordinating conjunction. Remember the acronym FANBOYS (For, And, Nor, But, Or, Yet, So). The comma goes before the connecting word.
4. Make one clause dependent. Add a subordinating conjunction (like 'because', 'although', or 'if') to one of the clauses, turning it into a dependent clause that leans on the other for support.

The most common mistake students make is assuming that a very long sentence is automatically a run-on. You can write a page-long sentence that is grammatically correct as long as the clauses are connected properly. Conversely, a run-on can be incredibly short, like 'It rained I got wet.'

Another frequent trap involves words like 'however', 'therefore', and 'moreover'. These are conjunctive adverbs, not coordinating conjunctions. If you put them between two independent clauses with just a comma, you create a comma splice. You must use a semicolon before them (e.g., 'It rained; therefore, I got wet.').