During his lifetime, H. L. Mencken was sometimes dismissed as a lightweight journalist. However, in the years since his death in 1956, he and his work have received increasing critical attention. The numerous works on Mencken issued in the 1960's and 1970's have added immeasurably to our knowledge. However, serious, in-depth studies of Mencken's compositional methods have not been made, a surprising fact in light of the wealth of materials available. This study addresses the need for such scholarship by examining Mencken's composition and revision of one of his finest books, Treatise on the Gods. The extant materials relating to this work include prepublication forms of both the 1930 and 1946 editions and a series of unpublished letters. These documents provide the data for a study of the evolution of Treatise on the Gods. A study of the comments Mencken made about the book, as well as the stylistic changes he made in its many forms, illuminates his working methods and his personality. The result indicates that Mencken was not a careless "cut and paste" composer, but rather was a methodical craftsman, who worked diligently to polish his prose. He was also a careful researcher, who wanted to·record facts accurately. Such efforts in Treatise on the Gods resulted in a durable work of scholarship and served to assure him a lasting place in literary history. / Master of Arts