Run-Ons and Comma Splices

When two complete sentences get jammed together without the right punctuation, the result confuses readers and costs points on the editing questions. The good news is that these errors follow a clear pattern, and once you see it, you can fix them in seconds.

A run-on sentence joins two independent clauses with no punctuation between them; a comma splice joins them with only a comma. Both mistakes push two complete thoughts into one sentence without a strong enough connector to hold them together properly.

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Spotting Fused Sentences and Comma Splices

Start by finding the independent clauses — the groups of words that could each be a sentence on their own. If two of them run together with nothing between, you have a fused (run-on) sentence: The rain stopped we went outside. Each half is complete, so they cannot simply collide. If the only thing between two complete thoughts is a comma, you have a comma splice: The rain stopped, we went outside. A comma is too weak to join two full sentences by itself. A quick test: cover everything after the comma or gap and check whether what remains is a full sentence; then do the same for the second part. If both stand alone, the punctuation between them must be stronger than a bare comma.

Four Ways to Fix Them

There are four reliable repairs. First, use a period and make two sentences: The rain stopped. We went outside. Second, use a semicolon when the ideas are closely related: The rain stopped; we went outside. Third, add a comma plus a coordinating conjunction (and, but, or, nor, for, so, yet): The rain stopped, so we went outside. Fourth, make one clause dependent with a word like “because” or “when”: When the rain stopped, we went outside. Wrong: I studied hard, I passed the test. Corrected: I studied hard, and I passed the test. Choose the fix that best fits how the ideas relate — a period for separate points, a connector when one idea leads to the next.

Watch: A Short Video Lesson

Khan Academy gives a clear overview to go with this lesson:

A Routine for Run-Ons and Splices

1. Find the independent clauses that could stand alone.
2. Check what sits between them — nothing, or just a comma?
3. Pick a fix: period, semicolon, comma plus conjunction, or make one clause dependent.
4. Reread to confirm each new sentence is complete.

Practice

1. What is a run-on sentence?
2. What is a comma splice?
3. Name all four ways to fix them.
4. Fix with a semicolon: “The store closed, we walked home.”
5. Fix with a conjunction: “It was late, we kept working.”
6. Why is a comma too weak on its own here?

Answers

1. Two independent clauses joined with no punctuation.
2. Two independent clauses joined with only a comma.
3. Period; semicolon; comma plus a coordinating conjunction; make one clause dependent.
4. “The store closed; we walked home.”
5. “It was late, but we kept working.”
6. Because each half is a complete sentence, and a comma cannot join two complete sentences alone.

Where This Fits in Your RLA Prep

These fixes build on complete sentences and clauses and connect to coordination and subordination. See every topic on the Language Arts Prep Hub.

Recommended Prep Books

Keep building momentum with a full study guide and practice tests:

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