High Quality Content by WIKIPEDIA articles! The American Federation of Musicians defines arranging as "the art of preparing and adapting an already written composition for presentation in other than its original form. An arrangement may include reharmonization, paraphrasing, and/or development of a composition, so that it fully represents the melodic, harmonic, and rhythmic structure" (Corozine 2002, p. 3). Orchestration differs in that it is only adapting music for an orchestra or musical ensemble while arranging "involves adding compositional techniques, such as new thematic material for introductions, transitions, or modulations, and endings...Arranging is the art of giving an existing melody musical variety" (ibid).