The purpose of this paper will be to compare the Hindemith theory of harmonic tension as set forth in his book, Craft of Musical Composition, with his actual use of harmonic tension in compositional practice. The compositions used for this study are Hindemith's Sonaten für Klavier, published in 1936, consisting of three sonatas*. Although these pieces were published one year before the theory book, it seems reasonable to assume that Hindemith was at least formulating the ideas that would go into his book, and quite possibly was already writing it. The copyright date of the book is 1937. Therefore, any conclusions derived from the following analysis will not be affected to any degree by the time lapse between the writing of the two works in question. Analysis of the Sonaten für Klavier by Paul Hindemith reveals the fact that each of the sonatas is very different from the other two; hence, conclusions which apply to all three works are not generally possible.