[littlemissattitude]

Usually, if it is a first edition, it will say "First Edition" somewhere on the publication data page. And usually, if it is a subsequent printing, but not a new edition (for example, not part of the first print run), it will still carry only the original publication date, not the "printed on" date. Usually, if it is a second or subsequent edition, it will carry both the original and the revised publication dates.

However, I have found that in practice, this differs from publisher to publisher, and you just have to take a good look at the publication data page to figure out if it is a first printing of a first edition or a subsequent printing. However, if it is a second or subsequent edition, it usually says that somewhere on the title page, especially if it is an academic book. If it isn't an academic book, it probably will indicate a second or subsequent edition, but again it can be pot luck as to where this is mentioned. The big houses are generally better about this than smaller houses.

This, anyway, has been my experience in a good number of years of writing papers in which sources have to be cited and listed in a bibliography, and having to figure out this sort of information.

Edited to add: Just because a book is listed as being a second or subsequent edition, this is not necessarily an indication that the previous editions have been in hardback or even formally published at all. I have a sixth edition of a law treatise on California law that I happend to pick up several years ago at a second-hand store for 80 cents; I bought it becuase the author of the book, the authority on California law for decades was scheduled to speak at my school, and I wanted to have a book to be signed without having to go out and spend a great deal of money on his then-current editions. Turned out I got a bargain. A representative from the man's publisher was with him when he came to speak, saw the book when I had him sign it, and offered me a substantial sum for it (I said no, of course). Apparently it is a fairly rare edition now. Part of it's rarity revolves around the fact that while it was the sixth edition of the book, it was the first edition that was actually published formally - the first five editions grew simply from the man's class notes when he was a law student. He started out by typing up and mimeographing (no xerox machines way back then) his notes and selling them to his fellow students.

This isn't something that happens very often, to be sure, but it is still something to keep in mind.