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Punctuation

In General

Use only one space after end punctuation (periods, exclamation points, question marks) and after colons and semicolons.

Apostrophes

When indicating the possessive for names, use an apostrophe followed by an s even when the person’s name ends in s or another sibilant.

• Kansas’s team
• Jones’s theorem
• Marx’s ideas

With a few exceptions, the possessive of a singular common noun is formed with the addition of an apostrophe and s, and the possessive of a plural common noun by the addition of an apostrophe only.

• the horse’s mouth
• the puppies’ tails
• the children’s desk

Do not use an apostrophe to indicate plurals, including the plurals of acronyms and abbreviations, unless confusion would result without the apostrophe (as in the first example).

• There are five s’s in that word.
• There are five 5s in that number.
• There were five PhDs in last year’s class.
• Five NGOs were represented at the conference.

Apostrophes are required for bachelor’s degree and master’s degree.

The following list includes names of offices and organizations on campus that commonly contain errors in apostrophe use. These are correctly punctuated. Note the absence or presence of apostrophes. Veterans has no apostrophes because it is a plural attributive noun.

• Presidents Leadership Class
• President’s Teaching Scholars
• Reserve Officer Training Corps
• Veterans Services
• Chancellor’s Leadership RAP

Colons

Use a colon to introduce a series or a list, especially a list preceded by as follows or the following.

Use a colon to introduce an explanatory phrase or sentence. Capitalize material after a colon if it constitutes a complete sentence.

• Conference participants should bring the following items: alarm clock, laptop computer, eye drops, coffee maker, and pillow.
• The implication of the chancellor’s challenge was clear: Students must not be overburdened by bureaucracy if they are to enjoy a fulfilling educational experience.

Commas

Between Proper Nouns

Use a comma between two proper nouns (or a year and a proper noun) to aid reading.

• When he gave his invited paper at the conference in June, Roy attracted a huge crowd.
• In 2006, George “Bud” Peterson was appointed chancellor of CU-Boulder.

In Complex and Compound Sentences

Use a comma before a conjunction that introduces an independent clause. Note that you do not need a comma before every and, but, because, and or. If what follows the conjunction is not a complete clause, you don’t need a comma (as in the second example).

• The orchestra is giving a concert in Macky Auditorium on Friday night, and the University Singers are performing in Grusin Music Hall on Saturday night.
• I like to go to football games and watch the marching band.

To Avoid Confusion

In general, don’t add commas just because you might pause when speaking a sentence, but do add them if they fall into any of the categories mentioned in this guide or if the meaning might be misconstrued without them, as in the following example:

• Bachelor’s degrees are offered in biochemistry and ecology and evolutionary biology. (It looks like three separate majors.)
• Bachelor’s degrees are offered in biochemistry, and ecology and evolutionary biology. (The sentence correctly shows two majors.)

With Appositives

Use commas with appositives that are nonrestrictive (not essential to the meaning of the sentence). Do not use a comma with appositives that are restrictive (essential to the noun it belongs to).

• Justin Time, director of Parking and Transportation Services, hired two additional students to monitor parking facilities during the conference.
• Professor Greene teaches the course Scientific Writing in Integrative Physiology.

With Dates

No comma is needed between a month and a year. Do use a comma before and after the year if month, date, and year are used.

• The deadline is April 1, 2007, for on-campus applicants and May 1, 2007, for off-campus applicants. A hiring decision will be made in May 2007.

With Introductory Phrases

Omit commas after short introductory phrases, except if confusion might result or if the introductory phrase ends with a date or proper noun and the main clause begins with a date or proper noun.

• On July 4, Chancellor Peterson will address a local veterans group.
• When it’s windy the kinetic sculpture on the north side of the ITLL is fascinating to watch.

In Lists (Serial Comma)

Use a comma before the conjunction and the final element in a list.

• Those in attendance included students, faculty and staff, and donors.
• NOT Those in attendance included students, faculty and staff and donors. (Without the serial comma, faculty plus staff plus donors could be construed as one category.)

With Nonrestrictive and Parenthetical Phrases

Use commas to set off nonrestrictive and parenthetical phrases.

• That bike, which is a racing model, cost more than my used car.
• My alternate route, the one I take when I have time, follows Boulder Creek.

With Place Names

Names of states (or countries) are enclosed in commas when they are preceded by a city or state.

• The conference will be held in Eugene, Oregon, but the planning meeting will be held in Frankfurt, Germany. The guest speaker is from Washington, D.C.

Dashes

Observe the distinction between hyphens, en dashes, and em dashes (“regular” dashes). Note that dashes do not convert automatically when you put copy on the Web, so you may want to use two hyphens for a dash when creating web copy.

En Dashes

Use en dashes between inclusive numbers.

• You’ll find the examples on pages 223–26 of your text.

Em Dashes

Em dashes are used to denote a sudden break in thought that causes an abrupt change in sentence structure. Do not overuse em dashes; they can interfere with the continuity of the look and the readability of your publication.

Traditionally, in all uses except most newspapers (and in some display typography, such as headlines), a dash is set without a space on either side. In certain formats and type sizes, adding a space before and after a dash can make the text look “gappy.”

• Each April participants representing a wide range of backgrounds gather in Boulder—a beautiful college town at the foot of the Rockies—for the Conference on World Affairs.

Ellipses

Use ellipses to indicate that material has been omitted from the middle of a quotation. Do not use ellipses at the beginning or end of a quotation even if you start or stop in the middle of the quoted sentence. Ellipses are created with three period characters, with one space on either side of each character:

. . . NOT ...

• Frank’s speech began with a request that audience members “leave all video cameras, tape recorders, and still cameras with the staff . . . at the entrance.”

When the omitted material includes a period, use a period plus ellipses:

• The Norlin Charge to the graduates reads, “You are now certified to the world at large as alumni of the university. . . . With hope and faith, I welcome you into the fellowship.”

Hyphens

Most questions about whether to hyphenate can be readily answered by consulting your dictionary. We prefer to follow the example of The Chicago Manual of Style: hyphenate compound adjectives that precede nouns only when necessary to avoid ambiguity.

Common uses for hyphens:

• abbreviations of CU campuses (CU-Boulder)
• compound adjectives such as well-prepared and self-sufficient, when used before a noun

Do not use a hyphen between a compound that begins with an adverb ending in ly:

• The Confusion Clearinghouse is an aptly named office.

Periods

Use periods in the following situations:

• when you come to the end of a declarative sentence
• when you come to the end of a quoted passage that also ends a sentence, even if it is not the end of the sentence in the original passage (rather than using ellipses)
• with some abbreviations (See Abbreviations; do not add an extra period if the abbreviation ends the sentence.)
• at the end of items in a vertical list, such as this one, if some or all of the list items are complete sentences (which these are not—and wouldn’t be even if the first word were capitalized)
• at the end of a vertical list that is punctuated (as this one is not) with commas at the end of each item (See Lists for more detail.)

A sentence can have only one terminal punctuation mark. When you’ve reached the terminal, you’ve reached the end.

Quotation Marks

Commas and periods always go inside quotation marks. Colons and semicolons always go outside quotation marks. With question marks and exclamation points, it depends: If the punctuation is part of the quotation, put it inside the quotation marks; if it’s not part of the quotation, put it outside.

Use quotation marks:

• to indicate the exact words that someone spoke or published
• the first time you refer to a nickname
• the first time you use a term or phrase ironically or sarcastically (don’t overuse)

Do not use quotation marks to set off clichés. Just don’t use the clichés.

Semicolons

Use semicolons in lists when items include commas (see Lists).

• CU officials at the meeting included: Bruce Benson, president; G. P. “Bud” Peterson, Boulder campus chancellor; and Ron Stump, vice chancellor for student affairs.