When showing possession of a word that ends in "s", is it correct to add " 's " or just the apostrophe?

Gus’s would be correct. I’ve seen it published both ways though only the former is proper. Now if you are using the “s” as a plural instead of a possessive you would add an “es” on the end, such as The Joneses.

just the apostrophe I’m pretty sure.

as in Jesus’ and such.

side note:
lurve for being a grammar nazi ;)

I always thought that it was a ‘s when singular and just an apostrophe when plural. So…

Gus’s truck is red.
The dogs’ owner kept them all in one pen.

I’m with Ivan.

@Ivan I remember specifically in grade school that it was always Jesus’
and not Jesus’s

”-add ‘s to the singular form of the word (even if it ends in -s):
the owner’s car
James’s hat (James’ hat is also acceptable. For plural, proper nouns that are possessive, use an apostrophe after the ‘s’: “The Eggles’ presentation was good.” The Eggles are a husband and wife consultant team.)”

Source: The OWL at Purdue

Btw, not that English teachers always teach perfect English but I used to teach Jr. High English.

According to The Elements of Style, if the word is singular or an irregular plural, you add ‘s to make it possessive. If it’s a regular plural, thus ending in -s already, you add ’ to make it possessive.

The Elements of Style allows that cases like Moses’ and Jesus’, though they don’t follow this rule, have been hallowed by time. I disagree.

Interesting question. I’ve been known to do it both ways.

According to this post at DailyWritingTips.com, apostrophes are used alone for ancient names, i. e., Jesus’ sword, Moses’ staff, etc. Modern names use an apostrophe s: Charles’s pen, James’s car, etc.

However, that post also points out that the Chicago Manual of Style, after explaining the rules above, states:

Those uncomfortable with the rules, exceptions, and options outlined above may prefer the system, formerly more common, of simply omitting the possessive s on all words ending in s—hence “Dylan Thomas’ poetry,” “Maria Callas’ singing,” and “that business’ main concern.” Though easy to apply, that usage disregards pronunciation and thus seems unnatural to many.

So in the end, we’re left as confused as ever because both ways seem to be correct. Isn’t English a wonderful puzzle of a language?

@drroombot: And don’t people who are interested in the byways and detours of English deserve a better rubric than grammar Nazi? Or at least an original synonym?

@gailcalled- I keep thinking of what @mattbrowne will say about grammar Nazi if he gets to this thread. I’m sure he’ll give @photographcrash a tongue lashing.

Some usage books say the first, some say the second, some say either. The first is more common.

If the name is one syllable, you can write it either way. Gus’ or Gus’s. But I have read some rules changed and that only Biblical names are allowed Jesus’ so I don’t know since I am older.

Variations in the use of the possessive marker continued for a long time, however; ‘As late as 1794 Washington Irving used apostrophes in only 38% of the possessives in his personal correspondence’ ( Greta D. Little, ‘The Ambivalent Apostrophe’, English Today, 8 Oct. 1986). By the mid-18c, however, the convention had extended to the possessive use of irregular noun plurals (children’s, men’s, and women’s clothing), but the treatment of regular s-plurals posed problems. Some grammarians of the period, for example, saw no need for the mark in such phrases as the soldiers hats, because nothing was omitted; indeed, there was debate as to whether a distinct plural genitive existed in Modern English. By the middle of the 19c, however, such forms as the soldiers’ hats were more or less established, but even so it appears from the evidence that there was never a golden age in which the rules for the use of the possessive apostrophe in English were clear-cut and known, understood, and followed by most educated people.

- Concise Oxford Companion to the English Language