Asprilio Pacelli, a composer and organist active in the late 16th and early 17th centuries, went down in the musical history of both Rome and the Polish-Lithuanian Commonwealth. In the Roman period of his work, he was associated for about seven years with the environment of the Jesuit Collegio Germanico. It was then that he published, among others, his Motectorum et psalmorum […] liber primus, which is the subject of this edition. In 1602 he took up the post of maestro di cappella at the court of Sigismund III Vasa, King of Poland and Sweden, a position he held for an exceptionally long time, more than twenty years, undoubtedly exerting a major impact on musical life in the Commonwealth during that period.