The Three Rules for Semicolon Use

Burgundy semicolonI love the semicolon. If a mark of punctuation could represent my personality, it would be the semicolon. The semicolon is stately and refined. It means business.

Like fine china, the semicolon is reserved for special occasions. Unlike the workaday period, showing up reliably at the end of every single sentence, or the whorish comma, inserting herself everywhere she is, and is not, wanted, the semicolon makes her appearance only when she is good and ready.

Perhaps this is why when I see a semicolon misused in a manuscript, I am overcome with a peculiar form of sadness. Correcting commas is like folding clothes: a mindless task I often perform. But I want that semicolon to be something special.

Dowager semicolonI long for its stateliness. I nod ever so slightly when I see a writer use it properly, as if to say, “well done, sir (or madam).” And when it is abused, I cringe—a slight, almost imperceptible motion.

The shame of it all is that semicolons only have three rules,* so it should be fairly easily to remember the rules and recognize when to use them. Here’s a quick refresher:

  1. Use a semicolon to separate items in a list when one or more of the list items contains internal commas.

Today, I went to store for a beef brisket, onions, and shallots; took my dog to the vet; and had my oil changed.

I will often see this rule misinterpreted to mean “use a semicolon to separate items in a long list,

X Compatibility determinations for recreational freshwater sportfishing; recreational sportfishing tournaments; recreational hunting; environmental education and interpretation; wildlife observation and photography; research and monitoring; commercial alligator harvest; commercial video and photography; beneficial use of dredge material; and commercially guided fishing on the East Cove Unit only are also included in the CCP.

or “use a semicolon to separate items in a list of long items.”

X We will recommend reinitiating consultation if new information reveals that the snag shearing method may affect these species or designated critical habitat in a manner or to an extent not previously considered; or it becomes necessary to use the traditional snagging method; or the action is subsequently modified in a manner that causes an effect on a listed species or on designated critical habitat.

Neither is correct.

  1. Use a semicolon to separate two independent clauses with a conjunctive adverb.

We disagreed with the judge’s ruling; however, we understood the legal basis for it.

Conjunctive adverbs are a unique class of words that require semicolons when they combine two complete sentences (independent clauses). For a complete list of conjunctive adverbs, visit my Resources page, and download the Chart of Transitional Expressions.

  1. Use a semicolon to separate two independent clauses when no conjunction is present.

To err is human; to forgive is divine.

Because these rules are intended for writers of professional, academic, and technical works, I recommend extreme caution in this instance, which asks the reader to infer the connection between the ideas. Poets are at liberty to juxtapose, whereas writers of formal text have a responsibility to explain the connections between their ideas.

Whether you, like me, long for the reprieve from this prosaic world that only the semicolon can offer, or you simply would like to know how to use it properly, I hope you found this information useful. Be sure to share it with your friends. And let me know what you think!

Michelle Baker is the Conservation Writing Pro. She teaches environmental scientists how to write more clearly. Contact her for all your writing training needs:



*Like all language rules, but especially those involving punctuation, these evolved over time. They are different  in British English than in American English. And the same rules do not apply to creative writing as to technical writing. I work specifically with writers of technical and regulatory documents in the environmental sciences, and these rules apply generally to anyone writing professional, academic, or technical work in Standard American English.



  1. Nice. Thank you.

  2. Would you punctuate these two examples in the same way?

    To err is human; to forgive is divine
    To err is human; to forgive divine (without the repeated “is”)

    To err is human, to forgive divine
    (This is how I’ve always known it. Not sure right off the top of my head, but I think it comes from Alexander Pope.)

  3. Jim, it would be correct to say:

    To err is human; to forgive, divine.

    I do not doubt that you have seen the quote punctuated the way you describe. You are right: the source is Pope, from his Essay on Criticism, and the rules for semicolons are different in England than in America, and they were different in the 18th c than they are today.

    If we combine the two independent clauses with only a comma, we commit an error known as a “comma splice.” This is one form of a run-on sentence, an egregious grammatical mistake because it seriously impedes understanding.

    If we omit the word “is,” we must indicate the omission. In formal writing, we do so with an ellipse (…), but, again, in informal or creative writing, a comma may be used instead.

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