For most of his adult life, Vivaldi was employed by the Ospedale della Pietà (Hospital, or Hospice of Mercy), one of the orphanages for ‘orphans and abandoned children’ in Venice. The boys were educated for a trade and the girls were trained to provide music for the church services and concerts to raise money. The sheer virtuosity of Vivaldi’s playing, and that of some of his pupils, attracted numerous visitors from all over Europe, bringing generous donations. He trained some of his best pupils to teach, which meant in later life he could absent himself for long periods as long as he kept supplying the Ospedale with new concertos fortnightly (they paid him 2 gold sequins a concerto).
Considering the Gloria is the most famous of Vivaldi’s sacred choral pieces, it is perhaps surprising there is so little known about its origins. It was most likely composed for the Ospedale della Pietà. Since the musical establishment had an almost entirely female staff (Vivaldi taught there in the presence of a chaperone), it will have been performed entirely by the ladies of the Ospedale, tenor and bass parts included. They performed behind a metal grille to shield them from the public view.