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Punctuation: Apostrophes

Apostrophe Basics

Apostrophes are punctuation marks used to indicate possession. The placement of an apostrophe depends upon the word you are making possessive.

  1. Singular possessive. Make a singular noun possessive by adding an apostrophe and an "s."
    Example: Long's theory (2003) suggested...
    Note that singular nouns ending in "s" still take an apostrophe and an additional "s" (i.e., Jones's theory).
  2. Plural possessive (regular). Make a plural noun possessive by adding an apostrophe.
    Example: The Nurses' Association published a code of ethics...
  3. Plural possessive (irregular). Make an irregular plural noun (e.g., "women" or "children") possessive by adding an apostrophe.
    Example: The Akron Children's Hospital.

Common Apostrophe Errors

There are some common apostrophe errors that are easy to avoid. Do not use an apostrophe:

  1. When making a noun plural.
    Incorrect: The studies' of Jones and Barnum...
    Correct: The studies of Jones and Barnum... or Jones's and Barnum's studies...
  2. When making an acronym or a number plural.
    Incorrect: CEO's of major corporations in the 1950's...
    Correct: CEOs of major corporations in the 1950s...
  3. When constructing contractions. Apostrophes can also be used to create contractions (words like "can't" and "didn't"); however, contractions are rarely used in academic writing.
    Incorrect: Walden University doesn't recognize Ground Hog Day as an official holiday.
    Correct: Walden University does not recognize Ground Hog Day as an official holiday.

Apostrophes Video

Note that this video was created while APA 6 was the style guide edition in use. There may be some examples of writing that have not been updated to APA 7 guidelines.