Grammar Rules on When to Use a Semicolon

Did you hear about the semicolons who were arrested? They were given back-to-back sentences.

Bad puns aside, semicolons play an important role in grammar. Presented as a period atop a comma, a semicolon's usage falls between the pause of a comma and the full stop of a period. This punctuation mark is what joins together a first independent clause with a separate, second independent clause.

Semicolons are grammatically powerful connectors that are most commonly used to join separate but closely related thoughts, or separate independent clauses, into a compound sentence.

Understanding the semicolon in your writing toolbox and knowing when to use a semicolon can help you create maximum impact. And, while semicolons may appear impressive (and therefore difficult), the grammatical rules they follow are quite simple.

A Semicolon Impacts Pace and Flow

Semicolons are most commonly used to separate complete thoughts in a single sentence, or to combine related thoughts into one sentence.

For example, consider these short sentences:

The author prefers to write books using a computer keyboard. She has written 28 books, three of which are best-sellers.

On their own, these sentences are fine. However, while it's true that these examples are grammatically correct when written as separate simple sentences, the effect is short and choppy. Using a semicolon to join these complete thoughts can add a rhythmic variation to the written word.

For example, here are the same two sentences joined by a semicolon:

The author prefers to write books using a computer keyboard; she has written 28 books, three of which are best-sellers.

Both examples are grammatically correct when written as either two sentences or as a single sentence joined by a semicolon. Knowing when to deploy a semicolon is often a matter of effect. A semicolon can help vary sentence length, and this can create an impact on the pacing of a narrative. Simply put, using a semicolon to connect two sentences can change the flow of writing and have a different effect on readers.

3 Questions to Remember About Semicolons

If the rules surrounding the use of semicolons seem confusing, there is a relatively simple way to double-check your decision to place a semicolon within a sentence. Ask these three questions to determine whether a semicolon is being used properly when joining two sentences, independent clauses or complete thoughts:

Can the words on either side of the semicolon stand alone as separate and complete sentences?
Can you use a coordinating conjunction like "and" or "but" or "or" in place of the semicolon you are using?
Could you replace the semicolon with a period or comma?

If the answer to all of these questions is yes, then you are most likely using a semicolon in a grammatically correct position.

The words that come before the semicolon should form a complete sentence; likewise, the words that come after the semicolon should form a complete sentence.

Look to Conjunctive Adverbs for Clues

Notice the last sentence in the previous section. See that semicolon before the word "likewise"? In this case, "likewise" is a conjunctive adverb. Conjunctive adverbs such as likewise, otherwise, nevertheless, moreover, therefore, then, finally, however and consequently are clues.

Consider the following sentences, for example:

I wanted to go for a walk to get some fresh air; also, the dog needed to go out.

News reports of tornado damage were greatly exaggerated; indeed, there were high winds but there was not a tornado.

Remember though, the semicolon only precedes a conjunctive adverb if the semicolon joins two independent clauses or complete sentences.

Organize Items in a List

Organizing items in a list is usually pretty straightforward. Let's say you are going to the grocery store and need to remember what items to purchase for fruit salad.

Your list may look like this:

apples, bananas, oranges and strawberries

But what if your list became a little more complicated, descriptive or detailed? Then a semicolon can keep it organized. When some of the items in a list already contain commas, deploying a semicolon becomes important. In cases such as these, a semicolon not only keeps the details attached to the correct nouns, but it can eliminate confusion.

For example:

shiny, red apples; ripe, yellow bananas; small, sweet oranges; and large, sweet strawberries

Using a semicolon to keep the correct words and phrases together in a sentence could look like this:

I bought ripe, yellow bananas; small, sweet oranges; and large, sweet strawberries; however, the store was out of shiny, red apples.

Semicolons Are Powerful Punctuation Marks

Used properly, a semicolon can be a powerful punctuation tool that signals to a reader that there is more to come in a sentence. Semicolons can lead to greater clarity in the written word and a better experience for the reader. Beware, though. If overdone, the impact of a semicolon begins to diminish. Used judiciously, semicolons pack a punctuation punch.