Abstract: Rabinal Achí, a modern opera, is based upon an ancient Mayan drama that originated in the thirteenth century from the highlands of Guatemala. The material in the opera is derived from the original Mayan text and music, either by direct quotation or through the creation of musical material informed by the text and music. External circumstances involving the various versions of the text and music also serve as a source from which the musical material is drawn. The compositional process of Rabinal Achí is detailed in this project report through the research and analysis of the various versions of the original text and music.