This thesis analyzes Andrea del Castagnos fresco of the Last Supper in the refectory of SantApollonia, Florence. This study investigates the details of the commission, Castagnos fresco in the iconographic tradition of representations of the Last Supper, the aspects which separate this Last Supper from previous examples in Florentine refectories, the frescos purpose in relation to its conventual setting, and also the artists use of both classicizing and contemporary elements and techniques. The central focus of my work is the significance of this fresco in terms of both the imagery Castagno employs and his possible sources. The purpose of this thesis is to recognize the innovative aspects of the fresco, as well as the role that Castagno played in the development of Florentine Renaissance art.