Giovanni Legrenzi was a prolific composer of vocal music and maestro di cappella at the Basilica di San Marco but his vocal works are not often studied as a part of the Venetian lineage with composers such as Willaert, de Rore, Zarlino, Monteverdi, Cavalli, and Vivaldi. Despite his being a prolific composer who had significant influence on the work of other musicians in the traditional canon, references to Legrenzi in standard music publications (Grout, Taruskin, Grove Music Online, etc.) are at best sparse, and largely biographical. This dissertation is one step to correct that pattern by creating a performance edition of Sacri e festivi concenti, Opera nona, one of Legrenzi's significant works near the beginning of his Venetian period. This collection of sacred music was published on 12 June 1667 in Venice though Legrenzi's exact whereabouts at the time remain uncertain. This phase of his career can be defined by his having sought more prestigious and lucrative employment. Having lived and worked in rural Lombardy and Ferrara, he made unsuccessful overtures in places such as Milan, Bologna, Vienna, and Paris. A full score has been produced by transcribing from the part books of the Bologna Museo copy, which will allow …