The Omoro Sōshi (1531–1623) is an indispensable resource for historical linguistic comparison of Old Okinawan with other Ryukyuan languages and Old Japanese. Leon A Serafim and Rumiko Shinzato offer a reference grammar, including detailed phonological analyses, of the otherwise opaque and dense poetic/religious language of the Omoro Sōshi. Meshing Western linguistic insight with existing literary/linguistic work in Ryukyuan studies, and incorporating their own research on Modern Okinawan, the authors offer a grammar and phonology of the Omoro language, with selected (excerpts of) songs grammatically analyzed, phonologically reconstructed, translated, and annotated.