The Mass of Saint Gregory was among a group of fine tapestries purchased by Philip the Handsome, duke of Burgundy, and his wife, Joanna of Castile, during the opening years of the sixteenth century as a gift for Joanna's mother, Isabella the Catholic. The word BRVXEL woven into the hem of Saint Gregory's robe indicates that this tapestry was woven in Brussels; it is the earliest piece signed in this way. Further, the stylized letters A-E L S-T suggest that the cartoon was owned by the weaver van Aelst, the leading Brussels tapestry merchant of the time. Woven in the richest materials, the tapestry demonstrates the increasing range of pictorial effects that the leading Brussels workshops could reproduce during this period. With its static and ornamental design, it also typifies the conservative style that characterized the finest contemporary Brussels compositions.