By all accounts, this is something that I should know intuitively, but alas I don’t.
George and Laura Smith are The Smiths, correct? Or is this the one place where we use an apostrophe in plurals, making them The Smith’s?
How about George and Laura Briggs? The Briggses? The Briggs’?
George and Laura Bush? The Bushes?
For pluralization of surnames, the apostrophe is incorrect. For possession it is needed but its form varies.
So the Bushes on the mailbox indicating that more than one Bush is in residence would be correct, whereas the Bushes’ Christmas presents will be opened together would be the way to indicate the plural possessive.
I have seen conflicting rules in reliable sources about the use of apostrophes for names (singular and plural) that end in s. The one I go by is that if the name is one-syllable, like James, it’s accurate to add apostrophe-s to it, making James’s. If there are more than one syllable in the name, the aprostrophe-s is replaced with just the apostrophe, as in Willis’.
I’d love to be proven wrong by some Ultimate Authority, but that’s the way I feel most comfortable after seeing several versions of “Correctness.”
Strunk (and White) says the singular possessive of most names is simply adding the “'s”: syllables aren’t a factor. Thus, Lucas’s car.
Oh for goodness sake!
Hee-hee! 
I have absolutely no authority on this, but a person (actually a college English teacher, so perhaps she had some authority) with a 3 syllable name ending in an “s” once told me that the rule was that if the name had an odd number of syllables, you added 's; otherwise just an apostrophe. I thought about this (who counts syllables, after all?) and decided that such a rule might conceivably develop out of a much more usable rule: if the final syllable bears a stress, usually secondary, then add 's, otherwise just an apostrophe. This is because the more-or-less standard pattern in English is to put a primary stress on the first syllable and secondary stress on all odd syllables thereafter. This is by no means universal, but it is very common. Thus iambic feet are so common that you will not notice if someone is speaking in that pattern. My wife once heard a lecture by Auden at which he announced halfway through that he had been speaking in iambic feet for fifteen minutes. Nobody had noticed.
I know that the Hospital where I work is St James’s Hospital- which always looks weird to me, but I have been assured is correct.
As mentioned, when you make a plural you never add an apostrophe.
Mr. Smith and his family, the Smiths
Mr. Byrnes and his family, the Byrneses
When you make the possessive from a word that ends in S, there are two different philosophies. Each publication will specify this in its own style guide. Neither has anything to do with the number of syllables or the accent on syllables.
Option 1:
If the word already ends in S, add only an apostrophe to make the possessive.
Mr. Byrnes’ car
The Byrneses’ houses
Option 2:
If the word is singular, add apostrophe S. If the word is plural, add only an apostrophe.
Mr. Byrnes’s car
The Byrneses’ house
Option 2 is the one specified by two or three companies I have worked for in their style guides, which is primarily for technical writing. If you pick up a newspaper or magazine, I expect you would find consistent use of one of this rules within the same publication.
When come back, bring cite.
Mr. and Mrs. Smith own a house. If I’m talking about them as a couple, they’re the Smiths. No apostrophe.
I might say that I’m “going to the Smiths’.” In this case, I’m eliding the noun “house” in conversational English, where a more formalized statement would be “I’m going to the Smiths’ house.” In that case, the plural possessive, ending in “-s’” is appropriate.
Slightly off topic, but virtually the only occasion one uses the apostrophe in forming a non-possessive plural is with typographical symbols (letters, numbers, symbols, etc.) used self-referentially. “He got straight A’s in college.” The modern tendency is to omit the apostrophe here unless the result might be misconstrued: Nothing is gained by the apostrophe in “at 6’s and 7s” vs. “at 6s and 7s” but “As” and “Is” might be misread as the two-letter words rather than “more than one A or I.” In such cases, good style calls for the traditional pluralization with apostrophe for clarity’s sake.
As for forming the plural possessive, I’ve always learned that the only proper form is with a terminal apostrophe. With singular nouns ending in -s, one opts between the lone apostrophe and the -‘s form for the possessive according to whether the spoken form adds an /iz/ syllable or not. "Good friend, for Jesus’ sake forbear" has no additional syllable to call for the additional -s, while “Jones’s store” is sounded as “JOAN-ziz” and does call for it. There was at one time a rule calling for omission of the -s when English possessives were formed from classical names ending in -s not in the possessive: “Paris’ abuction of Helen” but I have not seen this adhered to consistently in contemporary good writing.
Thanks for verbalizing another variation that makes good sense to me, beyond the one I already mentioned above. The idea that the punctuation mimics the sound is how I was trying to formulate a way to include that “rule” among the one(s) I prefer.
I agree with Polycarp. When writing or editing, my basic universals are:
[ul]
[li]No apostrophe for plural, even with all-cap abbreviations. (Exceptions made when confusion is an actual issue, like I’s or A’s.)[/li][li]Apostrophe-Ess for all singular possessives, no matter the syllables. I will occasionally omit the final Ess for tradition’s sake: Moses’, Jesus’, etc., are grandfathered exceptions. For other rare exceptions I consider, like Polycarp, how the word would be pronounced in normal speech. However I tend to err, even in such cases, on the side of including the final Ess, and allowing the potential pronouncer to use it or not.[/li][/ul]
Forgot to add: my overall guiding principle is to be consistent within a document, and to remain adaptable for such grayish areas between documents, depending on whom I’m editing or writing for. There are some absolutes in such things, but there are other things that require consideration and adaptability: commas, hyphens, colloquiallisms, etc.
Off on a tangent(?): I always use an apostrophe for plurals that don’t end in -s when they are used as a possessive. For example, Children’s Hospital. It has always looked odd to me to see signage for “Childrens Hospital” around here. But what’d you expect, it’s Los Angeles.
For singular nouns that end in S.
These cites are all from educational or other somewhat reputable source, not just random opinions:
This one subscribes to the just-the-apostrophe-if-it-ends-in-S-or-Z-or-X rule (the X and Z are new ones on me)
And one that subscribes to the apostrophe-plus-S-even-if-it-ends-in-S rule
and another
and another
And here one that sits on the fence, saying to add apostrophe-S but it’s acceptable to omit the S
These guys consider the pronunciation as a mitigating factor
So do these guys but use a different rule
And this one’s unique–it depends on how the next word starts
This one’s confusing, taking into account whether it’s a name, singular, plural, how it sounds and seems to give contradictory examples (Dickens’s, Moses’)
And I’ll give these guys the last word, which is "Since there is no agreement on this difficult problem, you must make your own choice. However, regardless of which option you choose, do remember to be consistent. "
I prefer the rule that you always use apostrophe-s to form the possessive of a singular noun. Jesus’s toenail, Jones’s gardenia, applesauce’s aroma. For the plural, you pluralize the word in whatever manner is appropriate. If the word now ends in an s, follow up with an apostrophe; if it does not, follow with an apostrophe-s.
Daniel
I think in general city and other official place names omit the apostrophe that would normally otherwise be found in proper writing. In this area we have Prince Georges County even though the Prince’s name was George. I am not sure but this may be to standardize such names for official directories or other legal purposes, ensuring that a misplaced apostrophe won’t foil a search for the name. The philosophy may have been extended for public signs out of habit.
It is, of course, Children’s Hospital in L.A., D.C., and every other I could find.
What if the word ends in s in both the singular and plural forms, through a pluralization rule other than the usual English one? This can happen with words of Latin origin, for example.
Are you sure? In Los Angeles, all their material leaves off the apostrophe from their name, e.g. website. I’ve lived here more than 30 years and I’ve never seen the apostrophe except maybe when written by some one out of town or new. It just looks strange to me. FYI, check out Boston’s Children’s Hospital’s website and compare it with Los Angeles’ Childrens Hospital’s website. (Did I use apostrophes correctly?)
Can you give an example of what you’re talking about?
Daniel