Purdue University North Central Writing Center Handout

Rules for Apostrophes

1.  Use the apostrophe to show  possession.

                 ex:  Paul’s hat                                 baby’s skin

                       car’s performance                 company’s reputation

2.  Do not use the apostrophe with possessive pronouns:  its, yours, her, his, theirs, ours, whose.

                 NOTE:  It’s is a contraction for “it is”.  Never use it’s as a possessive pronoun.

3.  If a singular noun ends in -s, add the apostrophe and -s when the word is short (one or two syllables) .  If the word contains more than two syllables, simply add an apostrophe.

                 ex:  James’s hat                   bus’s motor

                        class’s behavior                        Yeats’s poetry

                                                OR

                       Aristophanes’ plays            psychoanalysis’ expense

4.  Add the apostrophe after the -s words that form their plural with an -s or -es.

                 ex:  the boys’ games

                        the Joneses’ party

5.  Add an apostrophe -s to indicate the plurals of numbers and letters.

                 ex:  There are four i’s in Mississippi.

                        His favorite decade was the 1960’s.

                 NOTE:  The plural of years can be written with or without the apostrophe:                             (1990’s or 1990s).  Whichever style you  follow , be consistent.

6.  Add apostrophe -s to plural nouns not ending in  -s.

                 ex:  children’s clothes

                        women’s rights

7.  Use an apostrophe in contraction to show the omission of certain letters.

                 ex:  can’t  (cannot)              you’re  (you are)

                        they’re  (they are)                  he’s  (he is)