Like a semicolon, a colon can connect two independent clauses, but it has several other uses as well. Colons, like semicolons, should be used sparingly.
Joining Independent Clauses
A semicolon or colon joining two independent clauses signals a connection between them. When a semicolon is used, the nature of that connection is variable: the connection may be causal, sequential, oppositional, and so on. A colon, however, connects two clauses in a specific way, indicating that the second clause expands on the first. It alerts the reader to read on for an explanation or expansion of the first clause:
In that instant Brandon made a decision: he would fly to Toronto and propose to Sean.
Silvia slumped in her chair and closed her eyes: she had never felt so dejected.
Introducing a Series or List
Use a colon with the phrases as follows and the following.
To make a cake you need the following ingredients: butter, sugar, eggs, milk, flour, leavener, and salt.
Combine the ingredients as follows: first, cream the butter with the sugar; second, add the eggs and milk; third, add the flour, leavener, and salt.
Use a colon before a series or list only if the words that introduce the list make up a complete sentence:
To make a cake you need a few basic ingredients: butter, sugar, eggs, milk, flour, leavener, and salt.
If the words before the colon do not constitute a sentence, do not use a colon:
To make a cake you need butter, sugar, eggs, milk, flour, leavener, and salt.
Introducing Related Sentences
A colon may be used to introduce a series of related sentences:
Karen had the plan all worked out: She would take Dawn out to dinner for her birthday. While Karen and Dawn had dinner, Teresa would meet the guests at Karen’s house. Then Karen would bring Dawn to the house after dinner. Surprise!
A series of related questions is likewise introduced by a colon:
Karen started to worry: Would Teresa remember to pick up the cake? Would the guests arrive on time? And what would Karen do if Dawn wanted to go home after dinner?
Use colons to introduce a quotation when it is not integrated into the syntax of your sentence or otherwise requires a formal introduction:
Nabokov opens his autobiography with a statement on mortality: “The cradle rocks above an abyss, and common sense tells us that our existence is but a brief crack of light between two eternities of darkness.”
But use a comma after a verb of saying (e.g., says, exclaims, notes, writes):
As Nabokov writes, “The cradle rocks above an abyss, and common sense tells us that our existence is but a brief crack of light between two eternities of darkness.”
No punctuation is needed when the quotation is integrated into the syntax of your prose:
Nabokov writes that life is “a brief crack of light between two eternities of darkness.”
See the MLA Handbook 1.3.2 on using a colon to introduce block quotations.
Introducing a Rule or Principle
Use a colon to introduce the formal expression of a rule or principle:
Many books would be briefer if their authors followed the logical principle known as Occam’s razor: Explanations should not be multiplied unnecessarily.
Lowercase or Capital Letter after a Colon?
Use a lowercase letter when the word that follows the colon is normally lowercased:
Bonnie had to admit what was already obvious to her roommates: she was allergic to the cat.
Use a capital letter when the colon introduces
- a rule or principle
- several related sentences
- a capitalized word such as a proper noun
A Common Mistake
Do not use a colon after for example, that is, and namely. Use a comma instead:
There are many ways to flavor a cake—for example, with vanilla, with lemon or orange zest, or with cinnamon.
Olive or coconut oil can be substituted for butter in a vegan cake (that is, one made without animal products).
Cakes made with grated vegetables—namely, carrot cakes and zucchini cakes—stay moist for days.
Take the Quiz
Test yourself with our colon quiz!
Published 20 September 2017