It has been estimated that well over half of the books published during the European Reformation were in Latin, many of which have never been translated and have garnered little scholarly attention. Yet a good number of them have a direct bearing on the history of the Reformation and its actors. One such is Roger Ascham's Apologia pro caena dominica contra missam & eius praestigias ('A defence of the Lord's Supper against the Mass and its magic'). Written as a direct response to a series of religious debates held at Cambridge University at the start of Edward VI's reign, it was published some thirty years later in the name of Roger Ascham. Offered here for the first time is a modern edition that providing the Latin original with facing page English translation. As such the book functions both as a modern edition in its own right, as well as in conjunction with Lucy Nicholas's monograph ('Roger Ascham's Defence of the Lord's Supper') that explores the Apologia and the contextual background to Ascham and his work.