There have been 39 FoxTrot books' published so far, all by Andrews McMeel Publishing. Of the 39 books, 27 are collections and 12 are anthologies. The anthologies are composed of the two or three previous collections, and include Sunday strips in color, except for the newest anthology, The Best of FoxTrot.
Beginning with Death by Field Trip, the size and shape of the regular collections changed to accommodate a new Sunday strip layout. The books were also made smaller (and much less expensive) to give a larger gap between anthologies. NOTE: The collection "Math, Science, and Unix Underpants" is not a brand new collection, but rather a themed collection of previously published strips.
Originally, the anthologies were made up of the previous two smaller collections, with color Sunday strips (as opposed to black and white in the smaller books). Starting with FoxTrot: Assembled with Care, the anthologies are made up of the three previous smaller books. The newest anthology, The Best of FoxTrot, is made up of Bill Amend's favorites and it will be two volumes according to Amazon.