This paper reassesses an existing hypothesis regarding the rare iconography of Ambrogio Lorenzetti's 'Annunciation' in Montesiepi. A possible new text source is identifiable in a Tuscan lauda from the late 13th century. The lauda describes the Virgin's fearful reaction to Gabriel's announcement, mentioning specifically her fall to the floor and her impulse to embrace a column. An analysis of the Sienese devotional context would appear to corroborate this thesis. In fact, from the 13th century, Siena hosted several confraternities and was an important centre for the production of laudas. It is plausible, therefore, that the literary tradition of the laudas influenced Ambrogio's creativity, given his involvement in the Sienese confraternal environment. A further step would be to consider the laudas in interpreting the 'Maestà' of the same chapel. The depiction of the Virgin as Regina Coeli frequently recurs in such vernacular sacred literature.