Grammar Lesson: The Possessive Case

By — John Wiley & Sons, Inc.
Updated on Dec 15, 2010

The possessive case of a noun or pronoun indicates ownership or possession. Pronouns such as his, her, its, my, mine, your, yours, their, theirs, our, and ours are all possessive case words.

Here are several rules for the possessive case.

  1. Most singular nouns form their possessive by adding an apostrophe and an s. (the baboon's food; the girl's sweater; Marx's teachings; Burns's poetic lines; Dickens's characters)
  2. To form the possessive of a singular noun that ends with an s sound, take one of two actions.
    1. If a name of two or more syllables ends in an eez sound, the possessive is formed without an additional s. (Ulysses' friends; Archimedes' theories)
    2. Add an apostrophe and an s if the word would not be difficult to pronounce. (dress's cost; quartz's essence)
  3. Add only an apostrophe to form the possessive of a plural noun that ends in s. (the boys' gymnasium; the Murphys' home)
  4. If a plural noun does not end in s, add an apostrophe and an s. (the men's department; the mice's hiding spots)
  5. Use the possessive form for only the last name in compound nouns for organizations, literary titles, businesses, and relatives. If owned separately, use the possessive for both names.
      Tom's and Pete's reputations (separate reputations)
      Procter and Gamble's sales (combined ownership)
      mother-in-law's magazines (one woman's ownership)
      mothers-in-law's magazines (two or more women's ownership)
  6. For acronyms (words formed from the first letters of a series of words), add an apostrophe and an s.
      the NHL's (National Hockey League's) members
      AARP's (American Association of Retired People's) membership

A word used in the possessive case shows ownership. Possessive pronouns do not require apostrophes.

The singular possessive pronouns aremy, mine, your, yours, his, her, hers, and its.

The plural possessive pronouns are our, ours, your, yours, their, and theirs.

The possessive pronoun whose also does not require an apostrophe.

This house is theirs.

Their car is currently in the shop.

Your notebook and my textbook are in the school's cafeteria.

Is that package theirs or ours?

The movie has lost its appeal with her children.

His bike is locked up next to mine in your space.

Note: Though a noun that precedes a gerund (word that ends in -ing and functions as a noun) requires an apostrophe, the pronoun that does the same does not require one.

    Nina's selecting that prize was very interesting. (Nina's, a possessive noun/adjective, requires an apostrophe.)
    Her selecting that prize was very interesting. (Her, a possessive pronoun/adjective, does not require an apostrophe.)

Activity 1- The Possessive Case and Pronouns

Fill in each blank with a singular or plural possessive pronoun.

  1. ______ diagrams were studied by the medical staff.
  2. ______ friends organized a trip.
  3. Can you bring ______ photo album to ______ house tonight?
  4. Will they not forget to follow ______ directions to get to ______ home?
  5. These youngsters were happy about ______ choosing Friday for their party date.
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