Judging from the publishing date it looks like the paperback, but it can be
verified by pages.
Hardcover: 352 pages Publisher: Houghton Mifflin Company; 1st Marine edition (January 15, 2000) ISBN: 0618030093
Paperback: 368 pages Publisher: Mariner Books (July 12, 2001) ISBN: 0618127445
Cindy, as I mentioned, I am a novice at this. I got thinking about the book last night and double-checked the title page. This may well be the paperback edition. This is what I found:
A Mariner Book Houghton Mifflin Company Boston New York First Mariner Book Edition 2001 Copyright 2000 by Jacobus Communication Corporation ISDN 0-618-03009-3 ISDN 0-618-12744-5 (pbk.)
Hope I haven't made unnecessary extra work for you. Would you prefer this sort of thing off-list?