Singular nounsFor years, the standard was to form the possessive of all singular nouns by adding the apostrophe and s ('s). This rule was followed regardless of the final consonant. Today, however, the following exceptions are generally permitted:
Singular nouns not ending in "s"
The standard rule of adding 's applies.
the boy's toys (one boy)
Singular nouns ending in "s"
Add 's unless the next word begins with s.
the hostess's invitation
Special expressionsSome words ending in sibilants ("s" sounds) take only the apostrophe when followed by words beginning with the letter s.
for goodness' sake
Singular proper names ending in "s"
The use of only the apostrophe is recommended.
Charles' friend Joe Liles' arrangement Moses' laws
Plural nounsPlural nouns not ending in "s"
Add the 's to form the possessive.
the alumni's contributions
Plural nouns ending in "s"
Add only the apostrophe.
the tenors' music
Nouns plural in form, singular in meaning
Add only the apostrophe
United States' wealth
Joint possession, individual possession
Use a possessive form after only the last word if ownership is joint.
Fred and Vern's choreography plan is great.
Use a possessive form after both words if the objects are individually owned.
Fred's and Vern's uniforms were at the cleaners.
Follow the rules above in composing the possessive form of words that appear in specialized phrases.
a day's pay
Possessive pronounsPossessive personal pronouns ending in s do not use the apostrophe.
Notice that it's is a contraction of it is, not the possessive of the pronoun it. If an editor uses an apostrophe with a pronoun, he should double check to be sure that the meaning of the sentence calls for a contraction.
It's (it is) a wise dog that scratches its (possessive) fleas.