What Is a Run-On Sentence?
Clause (n): a unit of grammatical organization next below the sentence in rank and in traditional grammar said to consist of a subject and predicate.
— New Oxford American Dictionary
Search the internet for “run-on sentences” and you’ll likely find examples of long lines (some run-ons, some not) by William Faulkner, Charles Dickens, Lewis Carroll, and other authors famous for their verbosity. Some sites (which will go unnamed) tell you that one of the iconic lines of twentieth-century American literature—the first line of J.D. Salinger’s The Catcher in the Rye (1951)—is a run-on sentence.
If you really want to hear about it, the first thing you’ll probably want to know is where I was born, and what my lousy childhood was like, and how my parents were occupied and all before they had me, and all that David Copperfield kind of crap, but I don’t feel like going into it, if you want to know the truth.
This is, indeed, a long sentence—63 words and six commas, to be exact—but it is not a run-on. On the other hand, this sentence is:
Julia likes cats, however, she prefers dogs.
Just seven words and two commas, but a run-on. (By the way, that last line is a fragment, a sentence lacking even one independent clause.)
How is the second sample sentence a run-on if the first is not?
The answer hinges on the definition of a run-on sentence. Contrary to popular belief, run-on sentences are not defined by length or complexity; a 1,000-word sentence could be grammatically correct and a four-word sentence could be a run-on.
A run-on sentence is something far more precise. It’s a sentence that contains two or more independent (aka main) clauses not properly separated. Generally speaking, independent clauses can be separated by a period, a semicolon, a colon, a comma and a conjunction, or a dash (though not all of these solutions work for all sentences).
We might fix the run-on above to read:
Julia likes cats. However, she prefers dogs.
or, more commonly:
Julia likes cats; however, she prefers dogs.
or even better:
Julia likes cats, but she prefers dogs.
The reason why the original “Julia” sentence is a run-on is fairly arcane: a conjunctive adverb like “however” cannot separate two independent clauses. Students preparing for the SAT and ACT should learn how to identify independent clauses, dependent clauses, relative clauses, relative pronouns, conjunctions, subordinators (words that make clauses dependent), and conjunctive adverbs—all terms and ideas that need to be understood in order to master the art of avoiding and fixing run-ons and fragments. This is likely the most important cluster of grammatical issues to master for both tests.
But my purpose here is not to unpack the nuances of these issues (you’ll need to take a class for that). It is simply to note that preparing for the SAT and ACT requires that students begin to see conventional English sentences as things constructed along pretty exacting guidelines. Sentences, like machines, are objects made out of properly connected parts.
Like an automobile, a sentence is made of interlocking units. Just as there are many correct and incorrect ways to build a car, there are countless ways for the parts of a sentence to interlock correctly or not. And just as a good auto-mechanic sees a car for its parts and knows exactly what to do under the hood to fix a mechanical problem, SAT and ACT test-takers need to be able to see sentences as constructed things made of clauses, which need to be connected with the right tools and in the right ways.
This is precisely the kind of thinking at work in Salinger’s opening sentence in The Catcher in the Rye. The sentence is something of a master class in English grammar.
If you really want to hear about it, | the first thing | you’ll probably want to know | is | where I was born, | and what my lousy childhood was like, | and how my parents were occupied and all | before they had me, and all that David Copperfield kind of crap, | but I don’t feel like going into it, | if you want to know the truth.
This sentence contains nine clauses total, 7 dependent and 2 independent, all properly separated. A clause consists of, at minimum, a subject and a predicate. I have highlighted only those terms necessary to complete each subject and predicate and italicized all conjunctions used to connect clauses. Things get tricky at the beginning of the second clause, whose subject is “thing” and whose verb is “is,” followed by an entire dependent clause (“where I was born”) that acts as the object of the verb “is.” In this sentence, “you’ll probably want to know” acts as a dependent clause since it is contained within a larger independent clause.
As a whole, a good SAT or ACT grammarian should see this sentence like this:
Dependent clause 1, Independent clause 1 Dependent clause 2 Independent Clause 1 continued Dependent clause 3, and Dependent clause 4, and Dependent clause 5, Dependent clause 6, but Independent clause 2, Dependent clause 7.
We could dig into this complex sentence further by looking at, say, how Salinger subordinates those seven dependent clauses, or by considering how to identify when a clause begins and ends. But, again, the point here is not to explore all these complexities (though that’s an important task for those preparing for the SAT and ACT).
My point is at once much simpler and more challenging: it is to show you that sentences are made of smaller units called clauses, and that there are rules for connecting and separating these units from each other. This is all to say that improving one’s grammar isn’t about memorizing countless rules or running your eyes over countless pages of writing.
It’s first and foremost about changing the way you see sentences—as constructed machines made of individual parts rather than as finished wholes.
Stephen P. is a writer and teacher based in Los Angeles. He has taught literature and writing courses at several universities and has taught writing and reading at Elite Prep Los Angeles since 2010.