How short a book can be?

[Scout]

The War of Art: Break Through the Blocks and Win Your Inner Creative Battles is 190 pages, nonfiction and enlightening for creative types - or anyone battling procrastination or, for me, that resistance to getting started on doing something worthwhile.

[J.]

To the original question - a book can be as long or short as it needs to be to tell it's story. However, if the question is "How short can a book be in order for it to be traditionally published?" that depends on the publisher's guidelines. In print, perhaps excepting a smaller press that uses print-on-demand technology, it is a matter of what's cost-effective in book production, as well as a reader's standards. Generally an novel is in the 45,000-50,000 minimum range with historicals, fantasy often coming in much higher. A short story usually tops out at around 12,000 words, and the "in between" - is a novella.
There are certain categories - novellas, single short stories, even poetry collections or shorter memoirs that are not cost effective for a publisher; however many do very well in self-published e-formats.

[Charissa]

As long as the story needs. Then you have to find a publisher.