Commas in Complex Sentences
Essential Question
When you’re adding extra details and information to a sentence, how do you know when (and when not) to use a comma?
Grammar in the World
What Do I Know?
What do you already know about punctuating long sentences? Use this interactive exercise to find out.
Building Blocks
Grammar is a complex system and structure of language. Mizzou Academy Grammar Lab spotlights one skill (or block) at a time, but it’s often helpful to see how a skill works together with other, related blocks to build the language structure as a whole. You may find the following resource topics helpful as context for this lesson:
Learn About Commas in Complex Sentences
When we speak, we use cues like body language, hand gestures, or pauses to help our listeners recognize which points are the main ideas and which points provide context or extra detail. When we write, we need punctuation to do that for us. The additional information is called a nonrestrictive element in the sentence, and we add punctuation before and after a nonrestrictive element to set it apart
In a complex sentence (a sentence that has at least one independent clause and at least one dependent clause), the independent clause is the main idea. It is the essential point – the one that could stand by itself as a complete sentence because it has both a subject and a verb.
The dependent clause is the nonrestrictive element, the extra information. It cannot stand alone as a complete sentence because it starts with a subordinating word (such as because or although or which or that, for instance). It depends on the rest of the sentence to make sense.
In complex sentences, commas create a short pause between a dependent clause and an independent clause, which keeps the emphasis on the main idea, controls the pace of the sentence (so it doesn’t all run together), and helps to avoid confusion.
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When and where TO use a comma in complex sentences: |
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When a dependent clause comes at the beginning of the sentence, place a comma after the dependent clause. |
When the dependent clause comes first in a complex sentence, use a comma. Whichever kind of clause it is, an introductory subordinate clause should be followed by a comma. Because I’ve always had trouble with grammar, I never bothered much with commas. Now that I know the rules, I’m much more confident about my writing. |
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When a dependent clause interrupts the main (independent) clause, use commas both before and after the dependent clause. |
My English teacher, whom I have always admired, helped me understand commas. I try to share, when I have the time, my grammar tips and tricks with all my friends. Sometimes I’d really like to tell linguists, who write the grammar rules, to get rid of commas altogether. |
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When and where NOT to use a comma in a complex sentence: |
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In most cases, do not use a comma before a dependent clause when it follows an independent clause. |
Exception: If the sentence is too long or confusing without a comma, it’s okay to use one for clarity. I struggled for a long time with grammar and spelling and punctuation, so I was especially grateful for my English teacher junior year, who finally taught me about commas. My first priorities are still football and gaming and family time, but my grades improved so much junior year that I try to share my grammar tips and tricks with all my friends, when I have the time. |
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Do not use a comma after a dependent noun clause that acts as the subject of the sentence. |
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Do I Get It?
What have you learned about using commas in complex sentences? Use this interactive exercise to find out.