Possessive Form of Singular Nouns Ending with S

Many people struggle with the possessive case of singular nouns when the words already end with s. The general rule is this:
Form the possessive singular of nouns with �s.

Here are some examples:

• James�s cat
• Mrs. Jones�s attorney
• Dr. Seuss�s book

Exceptions

Of course, we�re talking about the English language, so we�re going to have some exceptions to the rule. While grammar books and style guides don�t necessarily agree on how to determine these exceptions, most consider a word�s pronunciation. Here is what a few of the books say:

• If pronunciation would be awkward with the added -�s, some writers use only the apostrophe. Either use is acceptable. (Diana Hacker, A Writer�s Reference)
• Exceptions are the possessives of ancient proper names in -es and -is [such as Achilles� and Isis�], the possessive Jesus�, and such forms as for conscience� sake, for righteousness� sake. (Strunk and White, The Elements of Style)
• With some singular nouns that end in -s, pronouncing the possessive ending as a separate syllable can sound awkward; in such cases, it is acceptable to use just an apostrophe. (Kirszner & Mandell, The Brief Holt Handbook)
• Since writers vary in the use of the apostrophe, it is not possible to make a hard and fast rule about the apostrophe in singular words ending in s.� Punctuate according to pronunciation. (John E. Warriner, English Grammar and Composition)