How do I address a woman with a hyphenated last name(e.g. Jane Smith-Lott) by last name? Is Ms.Smith-Lott OK?

You should address her Ms. Smith-Lott. You can't assume that she is married as the hyphenated last name could have been a result of her parents. Her parents may be Mrs. Smith (or Mrs. Smith-Lott) and Mr. Lott (or his name could have been Smith-Lott). This is the polite way to address her. After this, she will most likely tell you how to best address her, or not comment on it, in which case, your initial address of her was most likely correct.

If she goes by Ms. Smith-Lott, then you must call her Ms. Smith-Lott. To call her anything else would be akin to simply making up a name for her. Whether her hyphenated surname is a result of marriage or not really doesn’t matter because it doesn’t change the fact that her name is her name. On a personal note, I think hyphenated surnames are an excellent way for a family or an individual to show both personal independence and family unity.

Hyphenated Surnames

The Smith name is her maiden or former last name....Just use Lott

Ms. Smith-Lott sounds good to me.

You can always ask her: "What would you like to be called?"

I'd call her Smith-Lott and then ask her what her preference is.

I'm not sure. Then again, I'm not sure why a woman would use a hyphenated name? I think your assumption is correct, though...

Women like that drive me nuts.. just pick a damned name.

If you don't want to take your husbands name, then don't...

Most do it to feel more important or something, it is assanine.

The rule is to 'say' the whole thing.

"Hello Mrs. Goodman-Cronenburgh"

Must be a pain to sign checks

You could observe how she introduces herself to you or to others, and model that behavior.