Martin Buber's German-language play, Elija. Ein Mysterienspiel (Elijah: A Mystery Play), which was published in the year of his death, 1963, is probably the last work Buber produced. But despite the fact that in this bio-bibliographic sense the play holds a unique place in his corpus, the scholarship has not identified the work's importance and the full meaning of its appearance. This would not have been the case, had the play been read through literary categories, and above all through the category of genre. I argue that the play has a unique linkage with the Spanish tradition of the auto-sacramental, and exploring this linkage stands to facilitate a deeper understanding of the text and its relation to Buber's complete body of work and to central tenets of his thought.