Hello, According to the rules, it is Joe's / Tom's / James's car. But here in the United States, many people simply write: James' car. They feel that the second "s" is not necessary. Of course, they should pronounce it as "JameSES house." NOT: "James house." So if you want to follow the rules, write "James's house," Or if you want to do what most Americans now do, write "James' house." But please pronounce as it as "JameSES house." Sincerely, James

I agree with James. I would write James' pen but as he has already pointed out make sure you pronounce it as Jameses pen.