This Mass and the 8-voice double-choir setting of the Marian antiphon upon which he based it is some of Victoria's greatest music. (I wrote about his eight voice setting of the Salve here: Tomás Luis de Victoria (1548-1611) : Salve Regina a 8 | Saturday Chorale – mfi). I think it very likely that Victoria planned to set four Masses based on all four of his 8-voice settings of the great Marian Antiphons but in the event he completed only three before his death in 1611 this one which he first published in 1592, and his Missa Alma Redemptoris Mater and Missa Ave Regina caelorum. It's a parody Mass – Victoria took material from his setting of the antiphons and reworked it to produce a piece of music which quotes the original while being fresh and interesting in its own right. What's particularly interesting about his parody technique in the Missa Salve Regina is that he not only quotes his setting for eight voices but also his setting for six which he published twenty years earlier in 1572. You can hear this very clearly in the Credo at 'Crucifixus etiam pro nobis' where he quotes the 'Et Iesum …' verse from the 1572 composition.
Quotations from, and reworkings of the eight voice setting of the Salve which was first published in the Gardane edition of 1576 and then reissued in 1600 in Madrid are very clearly recognisable throughout the Mass and far more frequent. To give just two examples in the Kyrie he reworks the 'Ad te clamamus …' verse and in the Agnus dei he quotes and reworks 'Vita dulcedo …'. It's a very beautiful and intricate piece of music full of brightness and happiness as for example, when he breaks into triple-time during the Gloria at 'Gloria Dei Patris …' . Enjoy :-).
Video Source: Tomás Luis de Victoria (1548-1611): Missa Salve Regina Published on 23 Jun 2013 by markfromireland
Score Available from Nancho Alvarez's site in PDF and lilypond formats: partituras de Tomas Luis de Victoria