Do you use an apostrophe at the end of a word that ends in the letter “s”? We see this rule applied differently because different styles vary. 

For making the possessive form of singular common nouns that end in “s,” AP and Chicago styles call for an apostrophe followed by another “s.” But if the next word begins with an “s,” AP style prefers just an apostrophe. If the common noun is plural, both styles use just an apostrophe.



Singular common noun

  • AP and Chicago: The waitress’s annoyance at having to sing “Happy Birthday” for the 11th time in one night was obvious to everyone in the restaurant, including her manager. 
  • AP only: The waitress’ superb service earned her the most tips of the night. (Remember: The word “superb” begins with an “s,” so there’s no “s” after the apostrophe.)


Plural common noun

  • AP and Chicago: The four snakes’ habitats are wildly different.


Proper nouns

Use only an apostrophe if following AP style. In Chicago style, use an apostrophe-s if the following noun is singular and just an apostrophe if plural.

  • AP: Julia Roberts’ breakout role was in Pretty Woman.
  • Chicago: Julia Roberts’s acting abilities have improved over time.