Orlando di Lasso composed two sets of Lectiones ex Propheta Hiob: the first one most likely in 1558; the second was published in print in 1582. While the first set was composed according to the traditional eight modes, the second one presents some riddles concerning the tonal arrangement. This paper shows that the second set of Job Lessons was intended for liturgical use and performed within a complete polyphonic office for the dead by an anonymous composer of the first half of the 16th century. The tonal construction of the Job Lessons follows the modality of the surrounding responsories. There is further evidence that the performance of this office of the dead took place in 1580 when Duke Wilhelm V introduced the Roman rite to the Munich liturgy. Then the scribe Franz Flori replaced the old anonymous ‘invitatorium’ with a new composition (by Lasso?) with text according to Roman use, so that the ‘fürstliche Musik’ could perform ‘Die Vigilie auf Römisch’.