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Apostrophe-S vs. Apostrophe: Forming Possessives of Words Ending in S (or an S Sound)

I’m going to focus on the difference between how The Associated Press Stylebook and The Chicago Manual of Style handle possessives for words ending in s or an s sound. In short, is it Carlos’ stylebook or Carlos’s stylebook?

Both AP and Chicago styles take pronunciation into account, handling new syllables formed by back-to-back sibilants in their own way. The style that many of us are accustomed to—simply adding an apostrophe after the s (e.g., moss’ growth) regardless of how the words sound—is a “formerly more common” alternative practice, according to Chicago, one which it does not recommend. But just between you and me, you can use this shoot-from-the-hip style in personal e-mail, where you are also free to forgo capitalization completely. (This may or may not be a test.)

Whereas quote marks can face left or right, apostrophes only face one way.

The punctuation mark that most often gets mixed up with the apostrophe, by my estimation, is the single quotation mark. If smart (or curly) quote marks are toggled on, beware of employing a beginning single quote mark (6-shaped) to do the job of an apostrophe (9-shaped): Whereas quote marks can face left or right, apostrophes only face one way. (Tip: Remember the mark in don’t, or think of a backwards c.) Prepare to battle text-editing software which defaults to a beginning single quote mark when you begin a paragraph with an apostrophe or key it in after a space, such as for ’80s, ’tis, ’cause, or rock ’n’ roll (apostrophes, all of them).

General Rules for Forming Possessives

Plural Common Nouns Ending in S

AP and Chicago: Add an apostrophe—jinx!

  • the students’ questions
  • the teachers’ headaches

Singular Common Nouns Ending in S

AP: Add apostrophe-s unless the next word begins with s.

Chicago: Add apostrophe-s.

  • the duchess’s hat
  • the duchess’s style

Proper Nouns Ending in S

AP: Add an apostrophe.

  • Charlaine Harris’ books
  • the Joneses’ competition

Chicago: Add apostrophe-s if singular, and add an apostrophe if plural.

  • Socrates’s tea
  • the Obamas’ garden
  • Les’s moor

Nouns Plural in Form, Singular in Meaning

AP and Chicago: Add an apostrophe.

  • the series’ actors
  • the Academy of Motion Picture Arts and Sciences’ history

Special Case: Nouns Ending in an Unpronounced S

AP: Add an apostrophe.

  • Descartes’ thoughts

Chicago: Add apostrophe-s.

  • Camus’s existence
  • the debris’s cloud

Special Case: Singular Common Nouns Ending in S or an S Sound, Followed by a Word Beginning With S

AP: Add apostrophe.

  • for appearance’ sake
  • for conscience’ sake
  • for goodness’ sake

Chicago: Add an apostrophe if the word ends in s; otherwise, add apostrophe-s.

  • for appearance’s sake
  • for conscience’s sake
  • for goodness’ sake

Proper nouns ending in s follow previously stated styles (e.g., for Jesus’s sake in Chicago style).

Exception: Company Names With Apostrophe-S

AP: Use as is.

  • McDonald’s profits (not McDonald’s’ profits)

So, to answer the question posed in the beginning (Carlos’ stylebook or Carlos’s stylebook?), the first is in AP style, the second is in Chicago style. Let’s hope that Carlos picked the right stylebook.


  • AP, 2011: “apostrophe”; “Ask the Editor
  • CMOS, 16th edition: possessives, 7.15-21

Titles: Quote Marks, Italics, Underlining, or Naked?

Remember the days when your manual typewriter didn’t have a key for the number 1, so you used a lowercase letter L instead? And to type an exclamation point, you typed an apostrophe first, backspaced, and then typed a period beneath it? Sure you do, punk.

Clarification: I’m not that old; my high school was poor. We pasted our newspaper dummies together with wax and made type changes with a dull razor.

Well, we don’t type that way anymore, because technology has blessed us with 1s and !s on our keyboards. Likewise, because we are capable of rendering type in italics, you underline titles only when writing them by hand or using software that doesn’t italicize. As long as you remember that underlining equals italics and to never underline when you can italicize, you’re good.

You can get pretty far by following the “Big/heavy equals italics” (like books) and “Small/light equals quotes” (like poems) generalizations.

As for enclosing titles in quotation marks or italicizing them, you can get pretty far by following the “Big/heavy equals italics” (like books) and “Small/light equals quotes” (like poems) generalizations, but Associated Press style doesn’t italicize nothin’ and Chicago style has layers of specificity and if-then statements. Fun!

Because the Associated Press stylebook is not indexed and the manual for Chicago style covers title style in several sections (intermixed with name style and capitalization style), some title styles may have been inadvertently omitted due to oblivion on my part. Please send me a note if any oversight makes you twitch.

It’s all arbitrary, so go for clarity and sustainability.

Following is the breakdown between AP style and Chicago style. This is intended as a quick rundown or cheat sheet; for examples of each, please refer to the pages and sections indicated. “Neither” means that the usual headline-style (or title-style) caps still apply, but the title/name is naked as far as quotes and italics are concerned. (Capitalization for titles will be covered in a future blog entry.)

Note: Use Command-F or Ctrl-F to perform searches.


Titles for . . . AP Chicago
Albums Quotes (p. 62) Italics (8.192)
Almanacs Neither (p. 62)
Apps Neither (p. 62), e.g., Facebook, Foursquare Italics (8.193)
Art Quotes (p. 62) Italics (8.193)
Articles Quotes (8.175)
Bible Neither (p. 62)
Blog entries Quotes (8.187)
Blogs Italics (8.187)
Books Quotes (p. 62)—but the Bible and catalogs of reference material use neither Italics (8.166)—but book series and editions use neither (8.174)
Cartoons Italics (8.194)
Catalogs Neither (p. 62)
Chapters Quotes (8.175)
Classical music, nicknames Quotes (p. 63)
Classical music, identified by sequence Neither (p. 63)
Columns (in periodicals) Neither (8.175, 14.205)
Comic strips Italics (8.194)
Computer games and computer-game apps Quotes (p. 62), e.g., “Farmville” Italics (Chicago Style Q&A)
Computer software Neither for software such as WordPerfect or Windows (p. 62)
Conferences Neither (8.69)—unless it has “status,” then use quotes
Departments (in periodicals) Neither (8.175, 14.202)
Dictionaries Neither (p. 62)
Directories Neither (p. 62)
Drawings Italics (8.193)
Encyclopedias Neither (p. 62)
Essays Quotes (8.175)
Exhibitions (large) Neither (8.195)
Exhibitions (small) Italics (8.195)
Fairs (large) Neither (8.195)
Fairs (small) Italics (8.195)
Gazetteers Neither (p. 62)
Handbooks Neither (p. 62)
Journals Italics (8.166)—unless part of name of award, organization, etc. (8.170)
Lecture series Neither (8.86)
Lectures (individual) Quotes (p. 62) Quotes (8.86)
Magazines Neither (p. 159) Italics (8.166)—unless part of name of award, organization, etc. (8.170)
Meetings Neither (8.69)—unless it has “status,” then use quotes
Movies Quotes (p. 62) Italics (8.185)
Newspapers Italics (8.166)—unless part of name of award, organization, etc. (8.170)
Operas Quotes (p. 62) Italics (8.189)—for long musical compositions or instrumental works, see 8.189-8.190
Paintings Italics (8.193)
Pamphlets Italics (8.193)
Periodicals Italics (8.166), unless part of name of award, organization, etc. (8.170)
Photographs Italics (8.193)
Plays Quotes (p. 62) Italics (8.181)
Podcast episodes Quotes (8.187)
Podcasts Italics (8.187)
Poems Quotes (p. 62) Quotes (8.179)—unless book length, then treated as book (italics)
Radio episodes (in series) Quotes (8.185)
Radio programs and series Quotes (p. 62) Italics (8.185)
Reports Italics (8.193)
Short stories Quotes (8.175)
Songs Quotes (p. 62) Quotes (8.189)
Speeches Quotes (p. 62) Neither (8.75)—unless it has “status,” then use quotes.
Statues Italics (8.193)
Television episodes (in series) Quotes (8.185)
Television programs and series Quotes (p. 62) Italics (8.185)
Unpublished works Quotes (8.184)
Video blogs Italics (8.187)
Video-blog episodes Quotes (8.187)
Web pages and sections Quotes (8.186)
Websites Neither (8.186)

When it gets confusing, just remember these golden rules of copyediting:

  1. Whatever you choose, be consistent.
  2. But beware of having a tin ear.
  3. It’s all arbitrary, so go for clarity and sustainability.

Good luck.