Possessive apostrophes with plural nouns

To form a plural possessive, make the noun plural first, then add the possessive mark. Regular plurals ending in s usually take only an apostrophe after the s. Irregular plurals that do not end in s take apostrophe-s. The apostrophe shows ownership or association; it does not create the plural.

Form the plural before the possessive

Start with the singular noun. One teacher becomes teachers; then teachers' lounge shows a lounge associated with multiple teachers. One child becomes children; then children's room shows the irregular plural possessive. This two-step check prevents a common error: adding apostrophe-s to every plural regardless of how that plural is spelled.

Distinguish plural from possessive

An apostrophe does not make an ordinary noun plural. 'The student's arrived' is incorrect when the sentence means several students arrived. Write 'the students arrived.' If the sentence means a paper belonging to several students, write 'the students' paper.' Use the sentence's meaning to decide whether the noun is singular, plural, or possessive.

A three-question edit

1. How many people or things does the noun refer to? Make it singular or plural first.
2. Does the plural form end in s? If yes, add an apostrophe after the s; if not, add apostrophe-s.
3. Does the sentence actually show possession or association? If not, remove the apostrophe.

Common errors

• Writing student's when the owner is a group of students.
• Writing childrens' instead of children's.
• Adding an apostrophe to a plain plural, such as apple's for several apples.
• Using the plural possessive when the meaning is singular ownership.
• Relying on the final s alone without checking what the sentence means.

Distinguish shared and separate possession

When two names share one item, the apostrophe usually attaches to the final name: “Mina and Leo's project” means one project they share. If each person has a separate project, mark each name: “Mina's and Leo's projects.” For a plural noun that ends in s, place the apostrophe after the s: “the teachers' lounge.” The meaning determines whether the owners act jointly or separately.

Handle irregular plurals

Plural nouns that do not end in s take apostrophe-s: children's books, men's coats, and people's choices. First form the plural, then add the possessive ending. Plurals that do end in s take only the apostrophe: students' essays, buses' routes, and families' plans. Do not assume that every noun ending in s is plural; a singular noun such as class forms the possessive class's in many American style guides.

Use apostrophes for time and measure

Apostrophes also mark association or duration in expressions such as “a day's work,” “two weeks' notice,” and “three dollars' worth.” In the plural time expression, weeks is already plural, so its apostrophe follows the s. A hyphenated or compound noun can be possessive as a unit: “my sister-in-law's car.” For plural compounds, make the main noun plural first when possible, then add the mark: “my sisters-in-law's cars.”

Do not add apostrophes to possessive pronouns

Its, yours, hers, ours, and theirs show possession without apostrophes. “It's” means it is or it has; “its cover” means the cover associated with it. Similarly, who's is a contraction, while whose is possessive. The apostrophe rule for plural nouns does not apply to these pronouns. Expand a contraction to test it, and check whether the noun actually expresses ownership or association.

A meaning-first editing test

1. Identify the owner or group of owners.
2. Write the correct singular or plural noun form first.
3. Decide whether the sentence expresses possession, association, or a contraction.
4. Place the apostrophe according to the noun's final plural form.
5. Read the sentence again to confirm that the apostrophe changes the meaning as intended.

Key takeaway

Make the noun plural first. If that plural ends in s, place the apostrophe after the s. If it does not, add apostrophe-s. Add no apostrophe when the noun is only plural.

Add an apostrophe after a regular plural ending in s

To show possession with a regular plural noun that already ends in s, place the apostrophe after the s: the teachers’ lounge, the candidates’ results, the companies’ offices. The plural ending is already present, so another s is not ordinarily added. Check that the noun is plural before choosing the apostrophe position.

For an irregular plural that does not end in s, add apostrophe plus s: children’s books, women’s roles, people’s opinions. The form depends on how the plural is spelled, not on how many people own the item. A singular noun such as child takes ’s: the child’s book.

Distinguish joint from separate possession

For joint ownership, place the possessive marker on the final name or noun: Maya and Lee’s project means they share one project. For separate ownership, mark each owner: Maya’s and Lee’s projects can mean each has a project. The surrounding meaning must make the distinction clear.

An apostrophe can also mark omitted letters in a contraction, but possessive pronouns such as its, hers, ours, yours, and theirs do not use apostrophes. Do not confuse “the teachers’ room” with “they’re in the room” or “their room.” Identify whether the word names ownership or contracts words.

Avoid apostrophes in ordinary plurals

Do not use an apostrophe simply to make a noun plural: “three exam guides,” not “three exam guide’s.” Letters, numerals, and unusual symbols may use apostrophes in some style contexts for clarity, but ordinary plural nouns do not. Before adding a mark, ask whether the word is possessive or contracted.

• Regular plurals ending in s take an apostrophe after s.
• Irregular plurals not ending in s take ’s.
• Joint ownership usually marks the final owner; separate ownership marks each.
• Possessive pronouns do not take apostrophes.
• Do not apostrophize ordinary plurals.

Check the rule in context

For a regular plural noun ending in s, place the apostrophe after the s: teachers’ lounge, students’ projects. For an irregular plural that does not end in s, add apostrophe-s: children’s books, women’s roles. The possessive form of a singular noun usually adds ’s, even when the name already ends in s, though some style guides allow a terminal apostrophe in particular names. First make the noun plural if the meaning requires more than one, then form the possessive. “The teachers’ meeting” belongs to several teachers; “the teacher’s meeting” belongs to one. Do not use an apostrophe to make an ordinary plural such as reports or books.