Missa in honorem Beatissimae Virginis Mariae-Haydn's so-called Great Organ Solo Mass in E flat major is among those works by Joseph Haydn which early in its history enjoyed widespread dissemination. The E flat major Mass with an unusual scoring including two English horns in the orchestra was composed around 1770 during the first years of Haydn?s tenure as Music Director for the Court of Esterházy. Despite the readily playable effective part for organ employed prominently as a solo instrument in the piece the Missa in honorem Beatissimae Virginis Mariae which was composed for a Feast to the Blessed Virgin Mary is seldom performed today. The new critical edition hopes to stimulate new interest in this work.