Punctuation Rules: Colons and Semicolons

Contributed by:
Ivan
Here, students will revisit the rules of punctuation that govern the usage of colons and semicolons. Use the semicolon only if they separate two complete sentences.
1. Semicolons & Colons
Adapted from Real Good Grammar, Too by Mamie Webb Hixon
2. Semicolons Joining Sentences
Use a semicolon between two complete sentences. Each sentence on
either side of the semicolon must be complete with its own subject
and verb. Keep in mind that a semicolon functions the same way as a
period and a capital letter.
Not all poetry is serious and difficult to read and interpret. The poetry
of Maya Angelou, for instance, is rhythmic, folksy, and easy to read.
In these two sentences, the content is closely related, so we can tie
them together by substituting a semicolon for the period and the
capital letter.
Not all poetry is serious and difficult to read and interpret; the poetry
of Maya Angelou, for instance, is rhythmic, folksy, and easy to read.
3. Semicolons Joining Sentences
Use a semicolon between two complete sentences connected
by words such as however, therefore, consequently,
nevertheless, and then.
Dr. Jones created an information sheet to help her patients use
their medication properly; however, her patients’ blood tests did
not reflect improvement.
“Dr. Jones created an information sheet to help her patients
use their medication properly” is a complete sentence.
“However, her patients’ blood tests did not reflect
improvement” is also a complete sentence. The introductory
element “however” doesn’t change anything; we can still use
a semicolon to tie the two sentences together.
4. Semicolons with Items in a List
Use a semicolon between items in a series when the items have internal
I bought an old, dilapidated chair; a mahogany table, which was in beautiful
condition; and an ugly rug.
There are three items in the sentence above: the chair, the table, and the rug.
Because there are commas between adjectives describing the items, commas
between the items themselves might get lost in a sea of commas, obscuring the
number of items in the list. In this situation, semicolons are super-commas,
providing next-level punctuation to help us sort out our furniture purchases.
We are thinking about moving to Omaha, Nebraska; Gainesville, Florida; or
Memphis, Tennessee.
If we had used commas to separate the three locations in this sentence, the
internal commas separating the cities from the states would have made it
difficult to tell if there were three locations or six.
5. Semicolon No-No’s
Do not use a semicolon between an
independent clause and a phrase or a
dependent clause.
You should not make such inflammatory
statements; although they are correct.
“Although they are correct” is not a
complete sentence.
6. Semicolon No-No’s
Do not use a semicolon
interchangeably with a comma.
I enjoy sports; particularly tennis,
soccer, and fishing.
“Particularly tennis, soccer, and
fishing” is not a complete sentence.
7. Semicolon No-No’s
Do not use a semicolon to substitute
for a colon.
The military expects one thing from
its rank and file; obedience.
“Obedience” is not a complete
sentence.
8. Colons with Items in a List
Use a colon between a complete sentence and a list or
explanation. Note that a complete sentence must precede
the colon.
There is one common disease on this campus: computer
viruses.
The players came from all over the world: Germany,
Russia, Japan, Canada, and Australia.
Just one item, “computer viruses,” constitutes a list in
the first sentence. With five countries in the list, the
second sentence better fits our common understanding
of a list.
9. Colons with Items in a List
Use a colon with a list even if the positions of the list
and the complete sentence are reversed.
These are all words that describe my first few days in
college: impressive, overwhelming, exciting,
surprising.
Impressive, overwhelming, exciting, surprising: these
are all words that describe my first few days in
college.
Sometimes, reversing the order of the introductory
statement and the list creates a rhetorically effective
sentence.
10. Colons with “the Following”
Use a colon after “the following” and “as follows”:
The workshop will include the following topics:
anger management, stress management,
communication skills, and sexual harassment
The portion of this sentence that comes before the
colon is a complete sentence. The portion that
comes after the colon is a parallel list.
11. Colons Joining Sentences
Use a colon to separate two closely related sentences
without a conjunction.
Ian was dissatisfied with the photos he had taken: all
of them were out of focus.
“Ian was dissatisfied with the photos he had taken” is
a complete sentence. “All of them were out of focus”
is a complete sentence that explains something
important about the first sentence. We use a colon
instead of a semicolon here because the second
sentence does more than just continue the thought as
it would with a semicolon: the second sentence offers
a necessary explanation that completes the thought.
12. Colons with Quotations
Use a colon preceding a formal quotation
that is a complete sentence.
David always offered the same response
to questions about his relationship with
Gracie: “It’s nunya business.”
Note that there are complete sentences on
both sides of the colon.
13. Colon No-No’s
Do not place a colon before or after “namely,” or
“for example.”
We agreed to the plan, namely, to give Joseph a
surprise party.
A colon is shorthand for words like “namely” and
“for example,” so using a colon with those words
would be redundant. A colon would also
effectively end the sentence at “namely,” making
the first portion of the sentence a fragment.
14. Colon No-No’s
Do not place a colon after a verb (are, include, etc.) unless the
sentence ends with a verb.
The components of this history course are lecture, recitation, and
laboratory.
“Lecture,” “recitation,” and “laboratory” are the objects of this
sentence; a colon would effectively end the sentence at “are,”
making the first portion of the sentence a fragment.
There are two things that make us what we are: our heredity and
our environment.
The part of the sentence before the colon is a complete
sentence that ends with the verb “are.” In this case, the colon
does not create a fragment.
15. Colon No-No's
Do not place a colon after a preposition (such as,
with, etc.).
Included in our curriculum are many of the
physical sciences such as engineering, biology, and
chemistry.
A colon preceding the list of sciences would
effectively end the sentence at “such as,”
making the first portion of the sentence a
fragment.