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Punctuation Guide

The following list provides guidance on the most commonly used and misused punctuation marks.


Generally, omit periods in acronyms unless the result would spell an unrelated word.

Ampersand (&)

Use the ampersand when it is part of a company’s formal name. The ampersand should not be used in place of and. In MC unit names, and is standard.

Apostrophe (')

Add an apostrophe and an s to most singular nouns to form the possessive, and only an apostrophe for plural nouns (except for a few irregular plurals that no not end in s). If the noun ends in s, x, or z add an apostrophe and an s.

An apostrophe is never used to form the plural.

It is used to avoid confusion in plural nouns that are lowercased or are abbreviations.

  • The Rockville Campus’ building (singular proper noun ending in s)
  • the Williamses’ new house, but the Joneses (forming a plural, no apostrophe needed)
  • 2010’s heaviest snowstorm
  • the three Rs, the 1900s, threes and fours (forming a plural, no apostrophe needed)

Straight versus slanted apostrophes

For printed material, the typographer’s mark (“smart quotes”) is preferable to the straight one, which is more prevalent in Internet material and other software applications. MS Word automatically generates the preferred quotation mark.

Artwork (see also, Quotes, Italics, or Nothing?)

Italicize titles of paintings, drawings, and sculptures.

  • Grant Wood’s American Gothic; Rodin’s Thinker

Books and periodicals (see also, Quotes, Italics, or Nothing?)

Italicize titles of books and periodicals.

  • For Whom the Bell Toll, Newsweek, The Washington Post

Bullet Points

In bulleted lists, introduce the list with a short phrase or sentence, followed by a colon. Put a space between the bullet and the first word of each item in the list. Capitalize the first word following the bullet. Use periods, not semicolons, at the end of each section, whether it is a full sentence or phrase. In a short list of items, do not punctuate each item. Use parallel construction for each item in a list.

The MC website now contains resource pages in six different languages identified as most common among the MC student population:

  • Amharic
  • Chinese
  • French
  • Korean
  • Spanish
  • Vietnamese

The pages contain information about admissions and registration, financial aid, English as a second language classes, transfer credit information, and more.

When encouraging students to enroll in French courses, MC faculty cite compelling data:

  • French is spoken in more than 50 countries around the world.
  • It is the third most widely spoken foreign language.
  • French and English are the two official working languages for international government organizations, such as the International Red Cross, the UN Secretariat, and the International Olympic Committee.


Singular common noun ending in s.


Plural noun ending in s.

Commas (,)

Commas in City and State Names: Enclose states, provinces, and territories in commas to set it from the rest of the sentence.

  • The committee will meet at the Rockville, Maryland, location.

Comma in Dates: In text, insert commas after the date and the year.

  • He was born on July 11, 1955, in Eugene, Oregon.
  • The event will be held on July 11, 2019. (not 11th or 11th)

Comma in Proper Names: “Jr.” is no longer set off by commas; neither is a numeral suffix.

  • Alan Miller Jr. works at the College; but Henry James II does not.

Comma in Numbers: Insert a comma in numbers of more than three digits.

  • 1,000
  • $2,580

Comma in a Series: In lists of three or more items, use a comma before the word “and” and “or.”

  • They will serve breakfast, lunch, and dinner.

Dash (and hyphen)

In typesetting, three distinct symbols are used: hyphen (-), dash (–) also called an en dash, and em dash (—).

Hyphen: Use a hyphen in phone numbers and all fractions.

  • 240-567-7000
  • one-third
  • three-fifths 

En dash: Use an en dash (half the size of an em dash) to indicate a range. (No spaces on either side of the en dash.)

  • 1992–1993
  • pages 12–105
  • 10 a.m.–5:30 p.m.
  • Monday–Friday

Em dash: Use an em dash (made up of two hyphens) or parentheses to set off a full phrase when the phrase contains a series of words that must be separated by commas. Also, use an em dash to denote an abrupt change in thought in a sentence or an emphatic pause.

  • We will fly to San Diego in June—if the travel expense is approved.

Exclamation Point

Use only to express a high degree of surprise, incredulity, or other strong emotion. Avoid overuse; use a comma after mild interjections. End mildly exclamatory sentences with a period.

  • “Never!” she shouted.
  • We hope you will attend.
  • The gala was a great success.
  • Thank you for participating.


For titles of movies, television, radio programs, plays, works of art (paintings, drawings, sculptures), exhibitions, books, and periodicals, use italics. For a complete list, see Quotes, Italics, or Nothing.

  • One Flew Over the Cuckoo’s Nest (movie)
  • The Sopranos (TV)
  • WAMU’s Drive Time (radio show)
  • Sweeney Todd (play)
  • Rodin’s Thinker and Grant Wood’s American Gothic (artwork)
  • A Farewell to Arms (book)
  • The Washington Post, Newsweek (periodicals)


Do not hyphenate words beginning with pre, except: pre-dentistry, pre-engineering, pre-medicine, pre-medical technology, pre-optometry, pre-pharmacy, and similar words.


Generally, do not hyphenate prefixes when using a prefix with a word starting with a consonant. Use a hyphen if the prefix ends in a vowel and the word that follows begins with the same vowel, except for cooperate and coordinate.

  • semi-independent, ultra- and subsonic vibrations
  • non-native, anti-intellectual 

Note: Use a hyphen if the word that follows is capitalized: pre-World War I.


  • pre-election
  • pre-eminent
  • pre-empt
  • pre-establish
  • pre-exist