Semicolons have very specific uses and so are easy punctuation marks to use correctly. But there are a few rules to remember. In fact, there are only two occasions when you can use a semicolon:
- to join the clauses in a compound sentence and
- to separate the items in a list or series when there are other punctuation marks within the items themselves.
Using Semicolons to Join Clauses
It might be useful here for us to review for a minute what a clause is. As you recall, a clause is a group of words that go together and that contains both a subject and a verb. When that clause also expresses a complete thought, we call it an independent clause, and when we punctuate it with some kind of end punctuation (period, question mark, exclamation mark) we call it a sentence. Sometimes when the ideas expressed in the independent clauses are closely related, we might want to emphasize that relationship by joining the clauses to create a compound sentence. There are several ways to do that correctly, and each has its advantages. But we are concerned in this handout only with how to correctly use the semicolon to connect them.
Using the Semicolon Alone
You can use a semicolon all by itself to join two independent clauses when the ideas expressed in the clauses are closely related—usually you will want to save this option for places where and makes sense.
Let’s look at an example.
The florist arranged the flowers. We delivered the bouquet today.
These two sentences express ideas that are closely related. They are a sequence related to the delivery of a florist’s order, and they could logically be joined with and. So these two sentences are good candidates for using a semicolon alone to connect them. That sentence would look like this:
The florist arranged the flowers; we delivered the bouquet today.
Using the Semicolon with Conjunctive Adverbs
Sometimes, we might want to join two independent clauses whose ideas are closely related, but related in some other way than can be expressed adequately with and. For instance, let’s say there’s a cause and effect relationship between them—as in the following sentences:
The major gave an unclear order. The troops marched over the cliff.
These two sentences are obviously related, and the relationship could be expressed by and, so we could join them with a semicolon. We could write the sentence as
The major gave an unclear order; the troops marched over the cliff.
But and doesn’t seem to tell the whole story. There seems to be a cause and effect relationship suggested as well. To make that relationship more concrete we can begin the second sentence with a conjunctive adverb, like consequently or as a result.
The major gave an unclear order. Consequently, the troops marched over the cliff.
But because we have separated the sentences completely by using the period at the end, we have not indicated to our readers how close we think these ideas are. We can fix that by using a semicolon to connect them. But where does the semicolon go? Since consequently introduces the second sentence, the semicolon must go directly before it:
The major gave an unclear order; consequently, the troops marched over the cliff.
Occasionally, we may want to join two sentences whose relationship is one of contrast.
He did not perform the surgery. He did assist the surgeon to close the incision.
And won’t work here at all to express the relationship, so we probably wouldn’t want to use a semicolon alone to join the two clauses. In these cases, a better choice might be to use an appropriate conjunctive adverb, like however, to introduce the second clause.
He did not perform the surgery; however, he did assist the surgeon to close the incision.
Please note, you should make sure you actually begin the second clause with a conjunctive adverb and not a subordinate conjunction, like because, since, etc., because using the subordinate conjunction changes the second clause from an independent clause to a dependent clause which can’t ever have the status of a sentence and can’t be punctuated with a semicolon. Some of the most commonly used conjunctive adverbs include however, therefore, moreover, nonetheless, nevertheless, consequently, moreover, otherwise, and accordingly.
Using Semicolons in Lists and Series
The other way we can use semicolons is to separate the items in a list or series when one or more of the items already contain punctuation. For instance, consider how the following sentence uses semicolons to “chunk” information into items in the series—in this case, classes of instruments.
When you think about how an orchestra is organized, notice the strings, the violin, the viola, and the cello; the woodwinds, the clarinet and the oboe; and the horns, the trombone, the French horn, and the trumpet.
The items in this series that are organized or chunked with semicolons are
- the strings, the violin, the viola, and the cello
- the woodwinds, the clarinet and the oboe
- the horns, the trombone, the French horn, and the trumpet.
This sentence has quite a complicated structure: it contains series within a series.
Notice that each of the items in the more inclusive series, which names a class of instruments (strings…, woodwinds…, horns…), contains a more specific series that modifies it and that the items in the modifying series (the violin, the viola, and the cello, for example) are separated with commas. Because we used commas to separate the items in this modifying series, we need to find a different punctuation mark, the semicolon, to separate the larger series—the classes of instruments. And because we did use semicolons to separate the classes of instruments, it is clear to our readers that the more specific series are examples of specific instruments that belong to each class. If we used only commas to punctuate both series the readers wouldn’t have a clue how to chunk the information: the strings, the violin, the viola, and the cello, the woodwinds, the clarinet and the oboe, the horns…well, you get the picture.
So all that discussion can be boiled down to the following rule:
Use semicolons to separate items in a series if any of the items contain internal punctuation.
You can test your understanding of this handout by completing Student Success Center exercises available here.