Apostrophes are punctuation marks used to indicate possession; the placement of an apostrophe depends upon the word being made possessive. Apostrophes are also used in contractions; however, contractions are not common in academic writing.

Note the italicization, bolding, and highlighting used for emphasis in the examples on this page.

1. Singular possessive. Make a singular noun possessive by adding an apostrophe and an s.

See the examples below:

• Pavlov’s theory of classical conditioning is based on his experiments with dogs.
• The company’s code of conduct is included in the employee manual.
• Jones’s (2017) research revolved around online academic writing feedback.

Note that singular nouns ending in "s" still take an apostrophe and an additional "s" (e.g., Jones’s research).

2. Plural possessive (regular). Make a plural noun possessive by adding an apostrophe.

See the examples below:

• The Nurses’ Association has a code of conduct.
• The researchers’ methods were sound.
• I did not use companies’ private documents in my analysis.

3. Plural possessive (irregular). Make an irregular plural noun (such as "women" or "children") possessive by adding an apostrophe and an "s."

See the examples below:

• I distributed recruitment flyers at St. Paul Children’s Hospital.
• My goal was to explore the perceptions of participants who attended the women’s health care conference.

4. 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. See this APA Style Blog post for more information.

 

Instead of writing

• I didn’t receive responses from two of the companies I contacted.

Use the uncontracted form:

• I did not receive responses from two of the companies I contacted.

Some common apostrophe errors are easy to avoid. Do not use an apostrophe in the following situations:

1. When making a noun plural.

INCORRECT: I received the contact information for the teacher’s who attended the conference.

CORRECT: I received the contact information for the teachers who attended the conference.

2. When making an abbreviation plural. See APA 4.29 for more information.

INCORRECT: I asked the CEO’s to define their own leadership style.

CORRECT: I asked the CEOs to define their own leadership style.

3. When making a number plural. See APA 4.38 for more information.

INCORRECT: I initially limited my search to the publications within the last 5 years, but most of the seminal research cited in this document was written in the 1960’s.

CORRECT: I initially limited my search to the publications within the last 5 years, but most of the seminal research cited in this document was written in the 1960s.