Run-on Sentences: What They Are and How to Fix Them

A run-on sentence happens when two or more complete thoughts are joined without proper punctuation or connecting words. Even if the ideas are clear, the sentence becomes grammatically incorrect and harder to follow.

Run-on sentences are one of the most common issues in writing, especially when writers try to pack too much into a single sentence. But with a few simple techniques, they’re also one of the easiest problems to fix. In this article, you’ll learn what run-on sentences are, how to spot them, and how to correct them using clear, practical methods.

What Is a Run-on Sentence?

A run-on sentence occurs when two or more independent clauses are joined together without the right punctuation or a connecting word. These sentences may seem fine at first glance, but they often feel rushed, confusing, or grammatically incorrect.

It’s important to note that a run-on sentence isn’t defined by length. A sentence can be long and still be correct, or short and still be a run-on if it joins full ideas improperly.

Example:

❌ Maya loves playing piano she practices every evening.
(This sentence includes two complete thoughts with no punctuation or connectors.)

✔ Maya loves playing piano. She practices every evening.
(Each clause stands alone with proper punctuation.)

✔ Maya loves playing piano, and she practices every evening.
(Here, the clauses are joined with a comma and a coordinating conjunction.)

Learning how to recognize run-on sentences starts with understanding how full sentences should be connected. In the next section, we’ll look at the different types of run-on sentences and how they appear in writing.

Types of Run-on Sentences

Run-on sentences don’t all look the same. A sentence can break the rules of correct clause connection in different ways. Here are the most common types:

1. Fused Sentence

A fused sentence joins two independent clauses with no punctuation or connector at all.

Incorrect: The power went out we sat in the dark.
Correct: The power went out. We sat in the dark.

2. Comma Splice

This happens when a comma is used between two independent clauses without a coordinating conjunction.

Incorrect: The train arrived late, we missed our connection.
Correct: The train arrived late, so we missed our connection.

Correct: The train arrived late. We missed our connection.

3. Polysyndeton (Overuse of Conjunctions)

This involves joining several clauses with coordinating conjunctions but without a clear structure or punctuation. While sometimes used for style, it often leads to unclear sentences.

Incorrect: She went to the store and she bought milk and she saw a friend and they talked for an hour.
Better: She went to the store, bought milk, and ran into a friend she hadn’t seen in a while.

Understanding these variations helps you identify run-ons more easily and apply the right fix depending on how the sentence is structured.

How to Identify a Run-on Sentence

Identifying a run-on sentence isn’t about counting words—it’s about recognizing when two or more independent clauses are joined incorrectly.

Here’s how to check if a sentence is a run-on:

1. Look for More Than One Complete Thought

Each independent clause should be able to stand on its own as a complete sentence.

I finished my homework it was getting late.
(Two full ideas are present, but there’s no punctuation or connector.)

2. Use the “Imaginary Period” Test

Try placing a period where you think the sentence could break. If both parts make sense as complete sentences, you likely have a run-on.

The road was icy we drove slowly.
→ The road was icy. We drove slowly.
✔ Both parts work, so the original sentence is a run-on.

3. Check Your Punctuation

A single comma is not enough to separate two independent clauses. If that’s all you see, you’re likely looking at a comma splice.

Incorrect: I enjoy reading, I rarely find time for it.
Correct: I enjoy reading, but I rarely find time for it.

Spotting run-ons becomes easier with practice. In the next section, we’ll go over how to fix them correctly.

How to Fix Run-on Sentences

Once you spot a run-on sentence, there are several effective ways to correct it. The method you choose depends on the tone, length, and flow you want to achieve in your writing.

1. Separate into Two Sentences

Break the sentence into two complete thoughts using a period.

Incorrect: She loves writing she journals every night.
Correct: She loves writing. She journals every night.

2. Use a Semicolon

Semicolons connect two closely related independent clauses without a conjunction.

Correct: She loves writing; she journals every night.

3. Add a Comma and Coordinating Conjunction

Use a comma followed by a coordinating conjunction (for, and, nor, but, or, yet, so).

Correct: She loves writing, and she journals every night.

4. Use a Subordinating Conjunction

Turn one independent clause into a dependent clause using a word like because, although, or while.

Correct: Because she loves writing, she journals every night.
Correct: She journals every night because she loves writing.

5. Use a Semicolon with a Conjunctive Adverb

If you want to show a relationship (such as cause and effect), use a semicolon followed by a transitional phrase like however, therefore, or in fact.

Correct: She loves writing; therefore, she journals every night.

Each of these methods corrects the structure while preserving the original meaning. Choose the one that fits the tone and purpose of your sentence.

Common Causes of Run-on Sentences

Run-on sentences often happen when writers focus more on ideas than structure. They’re especially common in early drafts, informal writing, or when trying to sound conversational. Here are the most frequent causes:

1. Misunderstanding What a Sentence Is

Many run-ons come from not realizing that two complete thoughts need a connector or punctuation. If each clause can stand alone, they need to be separated or joined properly.

Example:
I woke up early I still missed the bus.
(Two complete ideas, but no proper punctuation.)

2. Overusing Commas or Conjunctions

Writers sometimes assume that adding a comma or repeating “and” is enough to connect thoughts.

Example:
He finished the project, he didn’t check the details.
(This is a comma splice, not a correct sentence.)

Example:
She ran and she called and she cried.
(Too many conjunctions without structure makes the sentence feel overwhelming.)

3. Trying to Cram in Too Much

When a writer tries to pack too many ideas into one sentence, it often leads to unclear connections or missing punctuation.

Example:
The presentation started late the sound system failed the audience got restless.
(This is a series of fused sentences.)

Run-on Sentences vs. Sentence Fragments

Run-on sentences and sentence fragments are often confused because they both break basic sentence rules, but they’re opposite problems.

Run-on Sentence: Too Much Packed Together

A run-on joins two or more complete thoughts without the right punctuation or connectors.

Example (Run-on):
She opened the window it was too warm inside.

This has two independent clauses but no punctuation or linking words.

Sentence Fragment: Incomplete Thought

A fragment is missing a subject, a verb, or a complete idea.

Example (Fragment):
Because she opened the window.

This sentence leaves the reader waiting for what happened next.

How to Tell the Difference:

• If the sentence feels too long or rushed and seems like two full thoughts pushed together → it’s likely a run-on.
• If the sentence feels cut off or unfinished → it’s likely a fragment.

FAQs