Definition

“Run-on sentences are independent clauses that have not been joined correctly. An independent clause is a word group that can stand alone as a sentence.”

Reference: Hacker, Diana, and Nancy Sommers. A Writer’s Reference, 8^th ed., Bedford/St Martin’s, 2015, p. 266.

Independent clauses include a subject and predicate (verb, object, and complements).

If you’re curious about what makes up a predicate, check the table of contents in most writer’s handbooks, including A Writer’s Reference.

Types of run-on sentences

Fused sentences

There is no punctuation between the two independent clauses.

Example: It was hard to choose which phone to buy the sales clerk was very helpful.

Comma splices

There is a comma between the two independent clauses without a coordinating conjunction.

Incorrect: It was hard to choose which phone to buy, the sales clerk was very helpful.

Correct: It was hard to choose which phone to buy, but the sales clerk was very helpful.

Recognizing run-on sentences

Can you identify more than one independent clause in the sentence? Are these independent clauses joined together with a semi-colon or a comma plus a coordinating conjunction, or with just a comma (a comma splice) or with nothing at all connecting them (a fused sentence)? In the section below, you will see examples of correcting run-on sentences by various means.

Correcting run-on sentences

Writers have multiple options for correcting run-on sentences. A number of options are discussed below.

1. Add a comma AND a coordinating conjunction between the two independent clauses

Coordinating Conjunctions: For, And, Nor, But, Or, Yet, So. (Tip: remember these words with the acronym FANBOYS)

Example: It was hard to choose which phone to buy, but the sales clerk was very helpful.

2. Add a semicolon between the two independent clauses

Joining two independent clauses this way implies that the two clauses are related and/or equal, or perhaps that one restates the other.

Example: It was hard to choose which phone to buy; the sales clerk was very helpful.

Transitional expressions

Optionally, put a transitional expression at the beginning of either clause followed by a comma.

Example: It was hard to choose which phone to buy; however, the sales clerk was very helpful

Conjunctive adverbs: finally, furthermore, however, moreover, nevertheless, similarly, therefore, thus.

Transitional phrases: after all, as a matter of fact, even so, for example, in addition, in conclusion, in fact, in other words, on the other hand.

Note: These are not complete lists. Check A Writer’s Handbook or a reputable website for more examples.

3. Add a subordinating conjunction at the beginning of either clause

Example: Even though it was hard to choose which phone to buy, the sales clerk was very helpful.

Example: It was hard to choose which phone to buy, although the sales clerk was very helpful.

Subordinating Conjunctions: After, although, as, because, before, if, in order that, once, since, so that, though, unless, until, when, whether, while.

Note: These are not complete lists. Check A Writer’s Reference or a reputable website for more examples.

4. Add a period between the two independent clauses

Example: It was hard to choose which phone to buy. The sales clerk was very helpful.