Guidelines for the use of the Apostrophe


Use an apostrophe to show ellipsis, that is the omission of one or more letters, numbers, or words in a standard contraction.

  • it is > it’s
  • they are > they’re
  • of the clock > o’clock
  • class of 1989 > class of ’89

PLURALS OF LETTERS, NUMBERS, AND WORDS NAMED AS WORDS (However, note that in some business writing, the apostrophes are left out.)

Use an apostrophe plus s for these plurals.

  • This essay has too many and’s.
  • I received 3 A’s and 2 B’s last semester.
  • His license plate has three 6’s
  • Be sure to dot your i’s and cross your t’s.


Use the apostrophe to indicate the possessive case of nouns and indefinite pronouns. Such nouns are marked with an apostrophe (and sometimes an “s”) to show where some thing belongs. (e.g., Ben’s cat; Americans’ government).

The first (and most common) rule is to add an ‘s to the noun or pronoun which the writer is identifying as owning or possessing something. These are commonly added to singular nouns or indefinite pronouns:

  • The dog’s ears flopped over.
  • Joe Schwartz’s house is being painted.
  • Bill Jones’s family moved to Mexico.
  • Doris’s essay on wells lacked depth.
  • The business’s chairman was forced to resign.
  • In today’s world, electronics rule.
  • Someone’s house is on fire.

An exception to the first rule is often applied to words in which the pronunciation would be made awkward, such as “Euripides,” “Moses” “Las Vegas,” “United States,” and “Jesus,” in which there is a repetition of the “s” sound. Such words are often made possessive by simple adding an apostrophe to them.

  • Jesus’ cross; Las Vegas’ list of jazz clubs, Euripides’ tragedies, Moses’ forty-year trek, etc.

An ‘s is also added to plural nouns which do not end in -s.

  • The children’s room was full of everybody’s coats.
  • The deer’s habitat is threatened.
  • The women’s role in religion is changing.
  • The geese’s flight patterns have remained the same.

The second rule is to just add an apostrophe (‘) to plural words that already end in an -s.

  • The teachers’ strike in Utah upset the governor.
  • State workers’ incomes have not risen for several years.
  • The students’ use of computers has increased each year.
  • The Petersons’ reunion had no activities for young people.
  • The Joneses’ home is getting a new roof.

With multiple nouns, the apostrophe is added only to the last noun if there is joint possession:

  • Prince Charles and Diana’s separation
  • Siskel and Ebert’s movie recommendations

However, if the possession is held separately, an apostrophe is added to each of the nouns:

  • Michael Jordan’s and Sammy Sosa’s careers
  • Paul Simon’s and Paul McCartney’s musical awards