Grammar Lesson: The Apostrophe

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

Here are useful rules for the apostrophe. Learn them well, and use them in your writing.

  1. Use an apostrophe to form the possessive of singular and plural nouns.
  2. Add an apostrophe and an s to form the possessive of a singular noun.

      Joe + 's = Joe's car
      day + 's = day's effort
      flag + 's = flag's colors
      glass + 's = glass's cost

    Note: If a plural noun ends in s, just add an apostrophe.

      cars + ' = cars' interiors
      televisions + ' = televisions' locations

    Note: If a plural noun does not end in s, add 's to the word.

      mice + 's = mice's home
      women + 's = women's department

    Note: If a name of two or more syllables ends in an eez sound, the possessive is formed without an additional s.

      the tales of Ulysses = Ulysses' tales
      the speeches of Orestes = Orestes' speeches
  3. To make the possessive of a compound word or the name of a co-owned business or organization, add 's to the last word of the name.
      brother-in-law's shoes
      Jackson and Meyer's law firm

Activity 1

Make each phrase possessive. Write your answer on the line provided.

  1. __________ the pictures owned by Mary
  2. __________ the coat owned by the sister-in-law of John
  3. __________ the speech delivered by Les
  4. __________ the space owned by Fred and Garrett
  5. __________ the address of Demetrius

Here are more situations involving the use of the apostrophe. Review them, and incorporate them into your writing.

  1. Use an apostrophe in contractions (words that combine two words into one).
  2. Form the plural of a lowercase letter by placing an 's after the letter.
      There are three a's in that word.
      Mind your p's and q's.
  3. You do not have to add an apostrophe to form the plural of capitalized letters, numbers, or symbols.

      We counted three Ts in that paragraph. (capitalized letters)
      How many 8s (or eights) are in that column? (numbers)
      Earl loves to use $s (or dollar signs) in his writing. (symbols)
  4. Use an apostrophe to show where the letter(s) is left out in a word or number.
      The Class of '18 = The Class of 2018
      Let's = Let us
      Gregory's = Gregory is or Gregory has
  5. Use an apostrophe to form the plural of an abbreviation that ends with a period.
      B.A.'s (or BAs) = Bachelors of Arts
      M.A.'s (or MAs) = Masters of Arts
      PhD.'s (or PhDs) = Doctors of Philosophy
      P.A.'s (or PAs) = Physicians Assistants
  6. Use an apostrophe to form the plural of an abbreviation that is not followed by a period. It is also acceptable to write the plural without the period.
      How many CD's (or CDs) do you own?
      How many different LSAT's (or LSATs) has Bertha taken?
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