Composers throughout history have transcribed the works of earlier masters as a method of instruction in composition. In 1788 Wolfgang Amadeus Mozart was contracted by Baron Gottfried van Swieten, prefect of the Imperial Library in Vienna, and distinguished patron of composers, to oversee a series of concerts of sacred works, especially those of Handel and Bach. Mozart undertook an arrangement of Handel's Messiah HV 56, in 1789, at the request of and under the supervision of the Baron. The resulting arrangement, Der Messias KV. 572, shows that significant changes were made to the original, especially in regard to the orchestral and vocal forces, but also in the addition of musical material, and the recasting of the solos, alongside the textual translation into German. After itemizing these changes, this thesis discusses two important issues that would have an impact on the interpretation of the work. The first issue concerns potential changes of affect and meaning as a result of the rhetorical implications of the aforementioned musical changes. The second issue relates to the performance practice of the work and its footing in both the Baroque and Classical styles. The thesis concludes with a reconsideration of transcribed works within a conductor's repertoire, programming options and educational strategies.