Apostrophes (’)

The apostrophe is a punctuation mark that serves three purposes: (1) to form a contraction, (2) to form the possessive case of a noun, and (3) to form the plural of an individual character. It is one of the most frequently misused punctuation marks because many contractions have the same pronunciation as unrelated possessives (e.g., “you’re” and “your”).

Using Possessive Apostrophes with Singular Nouns

The most common use of apostrophes in academic writing is to indicate possession. For a singular noun, the possessive apostrophe goes before the “s.”

Example
The sample’s consistency was too thin.

Possessive apostrophes can also be used with parenthetical citations in academic text. The proper way to do this depends on the academic field as well as journal and style guidelines. However, the following examples will demonstrate what is typically accepted.

Example
The analysis of Mercer et al. (2013) implies…
Incorrect
Mercer et al. (2013)’s analysis implies…
Correct
Mercer et al.’s (2013) analysis implies…

Using Possessive Apostrophes with Plural Nouns

For plural nouns that end in “s,” the possessive apostrophe goes after the “s.”

Incorrect
The sample’s consistencies were too thin.
Correct
The samples’ consistencies were too thin.

However, for plural nouns that do not end in “s,” the possessive apostrophe goes between the last letter and the added “s.”

Incorrect
The mices’ primary food source was found to be grass seeds.
Incorrect
The mice’ primary food source was found to be grass seeds.
Correct
The mice’s primary food source was found to be grass seeds.

Apostrophes with Possessive Pronouns

Unlike regular nouns, pronouns have possessive forms that do not involve the use of apostrophes. For example, the possessive form of the pronoun “him” is “his.”

Incorrect
He’s car is a blue Mini Cooper.
Correct
His car is a blue Mini Cooper.

Pronoun forms

Pronoun as Subject Possessive Pronouns Possessive Adjectives

First Person

I
We

Mine
Ours

My
Our

Second Person

You

Yours

Your

Third Person

He
She
It
They

His
Hers
Its
Theirs

His
Her
Its
Their

Apostrophes with Multiple Possessives

When it is necessary to indicate the joint possession of a single item for multiple nouns, only the final noun is written in possessive form.

Incorrect
The mouse’s and the hamster’s carrot was grown in the campus greenhouse.
Correct
The mouse and hamster’s carrot was grown in the campus greenhouse.

However, to indicate the distinct possession of multiple items for multiple nouns, all the nouns are written in possessive form.

Incorrect
Miller’s and Matthew’s publishing houses are both searching for new and emerging authors.
Correct
Miller and Matthew’s publishing houses are both searching for new and emerging authors.

Apostrophes with Contractions

A contraction is a shortened version of a word or words. The apostrophe in a contraction is placed in the location of omitted letters. Contractions are generally not used in academic writing. However, they are used frequently in colloquial speech and more casual texts.

Without Contraction
Eva does not have a pen.
With Contraction
Eva doesn’t have a pen.
Without Contraction
I have got a pen.
With Contraction
I’ve got a pen.

“Doesn’t” is a contraction of “does not,” and the apostrophe is placed where the “o” in “not” has been omitted. “I’ve” is a contraction of “I have,” and the apostrophe is placed where the “h” and “a” in “have” have been omitted.

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Apostrophes and Plurals

Using an apostrophe to pluralize a noun is a common error. Typically, apostrophes cannot be used to pluralize nouns.

Incorrect
The book’s are not arranged properly.
Correct
The books are not arranged properly.

Apostrophes and Surrounding Punctuation

An apostrophe is a part of a given word or contraction. As such, it should not be separated from the word or contraction by a space or another punctuation mark.

Incorrect
“The cats’,” she began, then stopped, distracted by a robin chirping outside.
Correct
“The cats,’” she began, then stopped, distracted by a robin chirping outside.

Separating an apostrophe from the word or within the contraction with a space can also cause the apostrophe to display backwards in a word processor. (‘)

Incorrect
The cat‘s bowl is blue.
Correct
The cat’s bowl is blue.

Possessive Pronouns vs. Contractions

Many possessives and contractions have similar pronunciations. For example, the possessive “its” and the contraction “it’s” share the same pronunciation. The same applies to “their” and “they’re” as well as “your” and “you’re.”

This confusion can be avoided by keeping in mind what the contraction is short for. It is easy to confuse “whose” and “who’s.”

Incorrect
Its Courtney’s birthday.
Correct
It’s Courtney’s birthday.
Incorrect
They’re car is parked outside.
Correct
Their car is parked outside.
Incorrect
Your expected at the courthouse in five days.
Correct
You’re expected at the courthouse in five days.
Incorrect
Whose the man standing outside?
Correct
Who’s the man standing outside?